Repository: you-dont-need/You-Dont-Need-Lodash-Underscore
Branch: master
Commit: b96a5a45b6c1
Files: 18
Total size: 154.5 KB
Directory structure:
gitextract_st3cxapu/
├── .github/
│ └── workflows/
│ ├── master.yml
│ └── pr.yml
├── .gitignore
├── .travis.yml
├── LICENSE
├── README.md
├── TEMPLATE.md
├── configuring.md
├── docs/
│ ├── .nojekyll
│ ├── README.md
│ └── index.html
├── index.js
├── lib/
│ └── rules/
│ ├── all.js
│ └── rules.json
├── package.json
└── tests/
├── index.js
├── lib/
│ └── rules/
│ └── all.js
└── unit/
└── all.js
================================================
FILE CONTENTS
================================================
================================================
FILE: .github/workflows/master.yml
================================================
name: Master
on:
push:
branches: [ "master" ]
# Allows you to run this workflow manually from the Actions tab
workflow_dispatch:
# Sets the GITHUB_TOKEN permissions to allow deployment to GitHub Pages
permissions:
contents: write
pages: write
id-token: write
jobs:
test:
name: Test
runs-on: ubuntu-latest
environment: testing
steps:
- name: 👌🏻 Checkout
uses: actions/checkout@v3
- name: Install dependencies
run: npm ci
- name: 🔎 Run tests
run: npm run test
- name: Run unit tests
run: npm run test:unit
================================================
FILE: .github/workflows/pr.yml
================================================
name: PR
on:
pull_request:
types:
- opened
- edited
- synchronize
# Allows you to run this workflow manually from the Actions tab
workflow_dispatch:
# Sets the GITHUB_TOKEN permissions to allow deployment to GitHub Pages
permissions:
contents: write
pages: write
id-token: write
pull-requests: write
jobs:
test:
name: Test
runs-on: ubuntu-latest
environment: testing
steps:
- name: 👌🏻 Checkout
uses: actions/checkout@v3
- name: Install Dependencies
run: npm ci
- name: 🔎 Run tests
run: npm run test
- name: Run unit tests
run: npm run test:unit
set-automerge:
name: Approve and automerge (only dependanbot PRs)
runs-on: ubuntu-latest
environment: testing
needs: [test]
if: ${{ github.actor == 'dependabot[bot]' }}
steps:
- name: Checkout
uses: actions/checkout@v3
- name: Dependabot metadata
id: dependabot-metadata
uses: dependabot/fetch-metadata@v1
with:
github-token: "${{ secrets.GITHUB_TOKEN }}"
- name: Approve a PR
run: gh pr review --approve "$PR_URL"
env:
PR_URL: ${{github.event.pull_request.html_url}}
GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
- name: Enable auto-merge for Dependabot PRs
if: ${{ steps.dependabot-metadata.outputs.update-type != 'version-update:semver-major' }}
run: gh pr merge --auto --squash "$PR_URL"
env:
PR_URL: ${{ github.event.pull_request.html_url }}
GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
================================================
FILE: .gitignore
================================================
node_modules
coverage
npm-debug.log
/.vscode
yarn.lock
================================================
FILE: .travis.yml
================================================
language: node_js
node_js:
- 10
- 12
- 14
script:
- yarn test
- yarn test:unit
after_success:
- yarn coveralls
================================================
FILE: LICENSE
================================================
MIT License
Copyright (c) 2018 You-Dont-Need
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
================================================
FILE: README.md
================================================
# [You don't (may not) need Lodash/Underscore](https://you-dont-need.github.io/You-Dont-Need-Lodash-Underscore/#/)
[](https://spectrum.chat/you-dont-need/lodash-underscore)
[](https://gitter.im/cht8687/You-Dont-Need-Lodash-Underscore)
Lodash and Underscore are great modern JavaScript utility libraries, and they are widely used by Front-end developers. However, when you are targeting modern browsers, you may find out that there are many methods which are already supported natively thanks to ECMAScript5 [ES5] and ECMAScript2015 [ES6]. If you want your project to require fewer dependencies, and you know your target browser clearly, then you may not need Lodash/Underscore.
You are welcome to contribute with more items provided below.
* If you are targeting legacy JavaScript engine with those ES5 methods, you can use [es5-shim](https://github.com/es-shims/es5-shim)
* Please note that, the examples used below are just showing you the native alternative of performing certain tasks. For some functions, Lodash provides you more options than native built-ins. This list is not a 1:1 comparison.
* Please send a PR if you want to add or modify the code. No need to open an issue unless it's something big and you want to discuss.
## Voice of Developers
> [Make use of native JavaScript object and array utilities before going big.](https://twitter.com/codylindley/status/692356631007342593)
> —<cite>Cody Lindley, Author of [jQuery Cookbook](http://shop.oreilly.com/product/9780596159788.do) and [JavaScript Enlightenment](http://shop.oreilly.com/product/0636920027713.do)</cite>
<!-- -->
> [You probably don't need Lodash. Nice List of JavaScript methods which you can use natively.](https://twitter.com/daniellmb/status/692200768556916740)
> —<cite>Daniel Lamb, Computer Scientist, Technical Reviewer of [Secrets of the JavaScript Ninja](https://www.manning.com/books/secrets-of-the-javascript-ninja-second-edition) and [Functional Programming in JavaScript](https://www.manning.com/books/functional-programming-in-javascript)</cite>
<!-- -->
> [I guess not, but I want it.](https://twitter.com/teropa/status/692280179666898944)
> —<cite>Tero Parviainen, Author of [build-your-own-angular](http://teropa.info/build-your-own-angular)</cite>
<!-- -->
> [I'll admit, I've been guilty of overusing #lodash. Excellent resource.](https://twitter.com/therebelrobot/status/692907269512642561)
> —<cite>@therebelrobot, Maker of web things, Facilitator for Node.js/io.js</cite>
## ESLint Plugin
<div align="center">
[](https://www.npmjs.com/package/eslint-plugin-you-dont-need-lodash-underscore)
[](https://www.npmjs.org/package/eslint-plugin-you-dont-need-lodash-underscore)
[](https://travis-ci.org/you-dont-need/You-Dont-Need-Lodash-Underscore)
[](https://coveralls.io/github/you-dont-need/You-Dont-Need-Lodash-Underscore?branch=master)
</div>
If you're using [ESLint](http://eslint.org/), you can install a
[plugin](http://eslint.org/docs/user-guide/configuring#using-the-configuration-from-a-plugin) that
will help you identify places in your codebase where you don't (may not) need Lodash/Underscore.
Install the plugin ...
```sh
npm install --save-dev eslint-plugin-you-dont-need-lodash-underscore
```
... then update your config
```json
"extends" : ["plugin:you-dont-need-lodash-underscore/compatible"],
```
For more information, see [Configuring the ESLint Plugin](configuring.md)
> [!IMPORTANT]
> Note that, while many Lodash methods are null safe (e.g. _.keys, _.entries),
> this is not necessarily the case for their Native equivalent. If null safety is critical for your application, we
> suggest that you take extra precautions [e.g. consider using the native `Object.keys` as `Object.keys(value || {})`].
## Quick Links
**[Array](#array)**
1. [_.chunk](#_chunk)
1. [_.compact](#_compact)
1. [_.concat](#_concat)
1. [_.difference](#_difference)
1. [_.drop](#_drop)
1. [_.dropRight](#_dropRight)
1. [_.fill](#_fill)
1. [_.find](#_find)
1. [_.findIndex](#_findindex)
1. [_.first](#_first)
1. [_.flatten](#_flatten)
1. [_.flattenDeep](#_flattendeep)
1. [_.fromPairs](#_frompairs)
1. [_.head and _.tail](#_head-and-_tail)
1. [_.indexOf](#_indexof)
1. [_.intersection](#_intersection)
1. [_.isArray](#_isarray)
1. [_.isArrayBuffer](#_isarraybuffer)
1. [_.join](#_join)
1. [_.last](#_last)
1. [_.lastIndexOf](#_lastindexof)
1. [_.reverse](#_reverse)
1. [_.slice](#_slice)
1. [_.without](#_without)
1. [_.initial](#_initial)
1. [_.pull](#_pull)
1. [_.unionBy](#_unionBy)
**[Collection*](#collection)**
> [!IMPORTANT]
> Note that most native equivalents are array methods,
> and will not work with objects. If this functionality is needed and no object method is provided,
> then Lodash/Underscore might be the better option. Bear in mind however, that all iterable
> objects can easily be converted to an array by use of the
> [spread operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax).
1. [_.each](#_each)
1. [_.every](#_every)
1. [_.filter](#_filter)
1. [_.groupBy](#_groupby)
1. [_.includes](#_includes)
1. [_.keyBy](#_keyBy)
1. [_.map](#_map)
1. [_.minBy and _.maxBy](#_minby-and-_maxby)
1. [_.orderBy](#_sortby-and-_orderby)
1. [_.pluck](#_pluck)
1. [_.range](#_range)
1. [_.reduce](#_reduce)
1. [_.reduceRight](#_reduceright)
1. [_.reject](#_reject)
1. [_.size](#_size)
1. [_.some](#_some)
1. [_.sortBy](#_sortby-and-_orderby)
1. [_.uniq](#_uniq)
1. [_.uniqWith](#_uniqWith)
**[Function](#function)**
1. [_.after](#_after)
1. [_.bind](#_bind)
1. [_.debounce](#_debounce)
1. [_.isFunction](#_isFunction)
1. [_.partial](#_partial)
1. [_.throttle](#_throttle)
**[Lang](#lang)**
1. [_.castArray](#_castarray)
1. [.cloneDeep](#_clonedeep)
1. [_.gt](#_gt)
1. [_.gte](#_gte)
1. [_.isDate](#_isdate)
1. [_.isEmpty](#_isempty)
1. [_.isFinite](#_isfinite)
1. [_.isInteger](#_isInteger)
1. [_.isNaN](#_isnan)
1. [_.isNil](#_isnil)
1. [_.isNull](#_isnull)
1. [_.isUndefined](#_isundefined)
**[Object](#object)**
1. [_.assign](#_assign)
1. [_.defaults](#_defaults)
1. [_.extend](#_extend)
1. [_.has](#_has)
1. [_.get](#_get)
1. [_.invert](#_invert)
1. [_.isPlainObject](#_isplainobject)
1. [_.keys](#_keys)
1. [_.mapKeys](#_mapKeys)
1. [_.omit](#_omit)
1. [_.pick](#_pick)
1. [_.pickBy](#_pickby)
1. [_.toPairs](#_topairs)
1. [_.values](#_values)
**[String](#string)**
1. [_.capitalize](#_capitalize)
1. [_.endsWith](#_endsWith)
1. [_.isString](#_isString)
1. [_.lowerFirst](#_lowerFirst)
1. [_.padStart and _.padEnd](#_padstart-and-_padend)
1. [_.repeat](#_repeat)
1. [_.replace](#_replace)
1. [_.split](#_split)
1. [_.startsWith](#_startsWith)
1. [_.template](#_template)
1. [_.toLower](#_tolower)
1. [_.toUpper](#_toupper)
1. [_.trim](#_trim)
1. [_.upperFirst](#_upperFirst)
**[Util](#util)**
1. [_.times](#_times)
**[Number](#number)**
1. [_.clamp](#_clamp)
2. [_.inRange](#_inRange)
3. [_.random](#_random)
## Array
### _.chunk
Creates an array of elements split into groups the length of size.
```js
// Underscore/Lodash
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]
_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]
// Native
const chunk = (input, size) => {
return input.reduce((arr, item, idx) => {
return idx % size === 0
? [...arr, [item]]
: [...arr.slice(0, -1), [...arr.slice(-1)[0], item]];
}, []);
};
chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]
chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]
```
#### Browser Support for Spread in array literals
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.compact
Creates an array with all falsy values removed.
```js
// Underscore/Lodash
_.compact([0, 1, false, 2, '', 3]);
// output: [1, 2, 3]
// Native
[0, 1, false, 2, '', 3].filter(Boolean)
// output: [1, 2, 3]
```
#### Browser Support for `array.prototype.filter`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.concat
Creates a new array concatenating array with any additional arrays and/or values.
```js
// Underscore/Lodash
var array = [1]
var other = _.concat(array, 2, [3], [[4]])
console.log(other)
// output: [1, 2, 3, [4]]
// Native
var array = [1]
var other = array.concat(2, [3], [[4]])
console.log(other)
// output: [1, 2, 3, [4]]
```
#### Browser Support for `Array.prototype.concat()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.difference
Similar to [without](#_without), but returns the values from array that are not present in the other arrays.
```js
// Underscore/Lodash
console.log(_.difference([1, 2, 3, 4, 5], [5, 2, 10]))
// output: [1, 3, 4]
// Native
var arrays = [[1, 2, 3, 4, 5], [5, 2, 10]];
console.log(arrays.reduce(function(a, b) {
return a.filter(function(value) {
return !b.includes(value);
});
}));
// output: [1, 3, 4]
// ES6
let arrays = [[1, 2, 3, 4, 5], [5, 2, 10]];
console.log(arrays.reduce((a, b) => a.filter(c => !b.includes(c))));
// output: [1, 3, 4]
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.drop
Creates a slice of array with n elements dropped from the beginning.
```js
// Underscore/Lodash
_.drop([1, 2, 3]);
// => [2, 3]
_.drop([1, 2, 3], 2);
// => [3]
// Native
[1, 2, 3].slice(1);
// => [2, 3]
[1, 2, 3].slice(2);
// => [3]
```
#### Browser Support for `Array.prototype.slice()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.dropRight
Creates a slice of array with n elements dropped at the end.
```js
// Underscore/Lodash
_.dropRight([1, 2, 3]);
// => [1, 2]
_.dropRight([1, 2, 3], 2);
// => [1]
// Native
[1, 2, 3].slice(0, -1);
// => [1, 2]
[1, 2, 3].slice(0, -2);
// => [1]
```
#### Browser Support for `Array.prototype.slice()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.fill
Fills elements of array with value from start up to, but not including, end.
> [!NOTE]
> `fill` is a mutable method in both native and Lodash/Underscore.
```js
// Underscore/Lodash
var array = [1, 2, 3]
_.fill(array, 'a')
console.log(array)
// output: ['a', 'a', 'a']
_.fill(Array(3), 2)
// output: [2, 2, 2]
_.fill([4, 6, 8, 10], '*', 1, 3)
// output: [4, '*', '*', 10]
// Native
var array = [1, 2, 3]
array.fill('a')
console.log(array)
// output: ['a', 'a', 'a']
Array(3).fill(2)
// output: [2, 2, 2]
[4, 6, 8, 10].fill('*', 1, 3)
// output: [4, '*', '*', 10]
```
#### Browser Support for `Array.prototype.fill()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 31.0 ✔ | ✖ | 32.0 ✔ | 8 ✔ |
**[⬆ back to top](#quick-links)**
### _.find
Returns the value of the first element in the array that satisfies the provided testing function. Otherwise undefined is returned.
```js
// Underscore/Lodash
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]
_.find(users, function (o) { return o.age < 40; })
// output: object for 'barney'
// Native
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]
users.find(function (o) { return o.age < 40; })
// output: object for 'barney'
```
#### Browser Support for `Array.prototype.find()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 25.0 ✔ | ✖ | 32.0 ✔ | 7.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.findIndex
Returns the index of the first element in the array that satisfies the provided testing function. Otherwise -1 is returned.
```js
// Underscore/Lodash
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]
var index = _.findIndex(users, function (o) { return o.age >= 40; })
console.log(index)
// output: 1
// Native
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]
var index = users.findIndex(function (o) { return o.age >= 40; })
console.log(index)
// output: 1
```
#### Browser Support for `Array.prototype.findIndex()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 25.0 ✔ | ✖ | 32.0 ✔ | 7.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.first
Returns the first element of an array. Passing n will return the first n elements of the array.
```js
// Underscore/Lodash
_.first([1, 2, 3, 4, 5]);
// => 1
// Underscore
_.first([1, 2, 3, 4, 5], 2);
// => [1, 2]
// Native
[1, 2, 3, 4, 5][0];
// => 1
//or
[].concat(1, 2, 3, 4, 5).shift()
// => 1
//or
[].concat([1, 2, 3, 4, 5]).shift()
// => 1
// Native (works even with potentially undefined/null, like _.first)
[].concat(undefined).shift()
// => undefined
[1, 2, 3, 4, 5].slice(0, 2);
// => [1, 2]
// Native with ES13
[1, 2, 3, 4, 5].at(0)
// => 1
//or
[].at(0)
// => undefined
```
#### Browser Support for `Array.prototype.slice()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
#### Browser Support for `Array.prototype.at()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
92 ✔ | 92 ✔ | 90 ✔ | ✖ | 78 ✔ | 15.4 ✔ |
**[⬆ back to top](#quick-links)**
### _.flatten
Flattens array a single level deep.
```js
// Underscore/Lodash
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]
// Native
const flatten = [1, [2, [3, [4]], 5]].reduce( (a, b) => a.concat(b), [])
// => [1, 2, [3, [4]], 5]
const flatten = [].concat(...[1, [2, [3, [4]], 5]])
// => [1, 2, [3, [4]], 5]
// Native(ES2019)
const flatten = [1, [2, [3, [4]], 5]].flat()
// => [1, 2, [3, [4]], 5]
const flatten = [1, [2, [3, [4]], 5]].flatMap(number => number)
// => [1, 2, [3, [4]], 5]
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4 ✔ |
#### Browser Support for `Array.prototype.flat()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |
#### Browser Support for `Array.prototype.flatMap()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |
**[⬆ back to top](#quick-links)**
### _.flattenDeep
Recursively flattens array.
```js
// Underscore/Lodash
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]
// Native
const flattenDeep = (arr) => Array.isArray(arr)
? arr.reduce( (a, b) => a.concat(flattenDeep(b)) , [])
: [arr]
flattenDeep([1, [[2], [3, [4]], 5]])
// => [1, 2, 3, 4, 5]
// Native(ES2019)
[1, [2, [3, [4]], 5]].flat(Infinity)
// => [1, 2, 3, 4, 5]
const flattenDeep = (arr) => arr.flatMap((subArray, index) => Array.isArray(subArray) ? flattenDeep(subArray) : subArray)
flattenDeep([1, [[2], [3, [4]], 5]])
// => [1, 2, 3, 4, 5]
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 7.1 ✔ |
#### Browser Support for `Array.prototype.flat()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |
#### Browser Support for `Array.prototype.flatMap()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |
**[⬆ back to top](#quick-links)**
### _.fromPairs
Returns an object composed from key-value pairs.
```js
// Underscore/Lodash
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }
// Native
const fromPairs = function(arr) {
return arr.reduce(function(accumulator, value) {
accumulator[value[0]] = value[1];
return accumulator;
}, {})
}
// Compact form
const fromPairs = (arr) => arr.reduce((acc, val) => (acc[val[0]] = val[1], acc), {})
fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }
// Native(ES2019)
Object.fromEntries([['a', 1], ['b', 2]])
// => { 'a': 1, 'b': 2 }
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
#### Browser Support for `Object.fromEntries()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
73.0 ✔ | 79.0 ✔ | 63.0 ✔ | ✖ | 60 ✔ | 12.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.head and _.tail
Gets the first element or all but the first element.
```js
const array = [1, 2, 3]
// Underscore: _.first, _.head, _.take
// Lodash: _.first, _.head
_.head(array)
// output: 1
// Underscore: _.rest, _.tail, _.drop
// Lodash: _.tail
_.tail(array)
// output: [2, 3]
// Native
const [ head, ...tail ] = array
console.log(head)
// output: 1
console.log(tail)
// output [2, 3]
// Native replacement for _.head in ES13
array.at(0)
// output: 1
```
#### Browser Support for Spread in array literals
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |
#### Browser Support for `Array.prototype.at()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
92 ✔ | 92 ✔ | 90 ✔ | ✖ | 78 ✔ | 15.4 ✔ |
**[⬆ back to top](#quick-links)**
### _.indexOf
Returns the first index at which a given element can be found in the array, or -1 if it is not present.
```js
// Underscore/Lodash
var array = [2, 9, 9]
var result = _.indexOf(array, 2)
console.log(result)
// output: 0
// Native
var array = [2, 9, 9]
var result = array.indexOf(2)
console.log(result)
// output: 0
```
#### Browser Support for `Array.prototype.indexOf()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.intersection
Returns an array that is the intersection of all the arrays. Each value in the result is present in each of the arrays.
```js
// Underscore/Lodash
console.log(_.intersection([1, 2, 3], [101, 2, 1, 10], [2, 1]))
// output: [1, 2]
// Native
var arrays = [[1, 2, 3], [101, 2, 1, 10], [2, 1]];
console.log(arrays.reduce(function(a, b) {
return a.filter(function(value) {
return b.includes(value);
});
}));
// output: [1, 2]
// ES6
let arrays = [[1, 2, 3], [101, 2, 1, 10], [2, 1]];
console.log(arrays.reduce((a, b) => a.filter(c => b.includes(c))));
// output: [1, 2]
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.takeRight
Creates a slice of array with n elements taken from the end.
> [!IMPORTANT]
> Native slice does not behave entirely the same as the `Lodash` method. See example below to understand why.
```js
// Underscore/Lodash
_.takeRight([1, 2, 3]);
// => [3]
_.takeRight([1, 2, 3], 2);
// => [2, 3]
_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]
// Native
[1, 2, 3].slice(-1);
// => [3]
[1, 2, 3].slice(-2);
// => [2, 3]
[1, 2, 3].slice(-5);
// => [1, 2, 3]
// Difference in compatibility
// Lodash
_.takeRight([1, 2, 3], 0);
// => []
// Native
[1, 2, 3].slice(0);
// => [1, 2, 3]
```
#### Browser Support for `Array.prototype.slice()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.isArray
Returns true if given value is an array.
```js
// Lodash
var array = []
console.log(_.isArray(array))
// output: true
// Native
var array = []
console.log(Array.isArray(array));
// output: true
```
#### Browser Support for `Array.isArray()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 10.5 ✔ | 5.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.isArrayBuffer
Checks if value is classified as an ArrayBuffer object.
```js
// Lodash
_.isArrayBuffer(new ArrayBuffer(2));
// output: true
// Native
console.log(new ArrayBuffer(2) instanceof ArrayBuffer);
// output: true
```
> [!WARNING]
> You will get the wrong result if you get `ArrayBuffer` from another realm.
> [See details](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof#instanceof_and_multiple_context_e.g._frames_or_windows).
#### Browser Support for `instanceof`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.join
> [!IMPORTANT]
> Not in Underscore.js
Joins a list of elements in an array with a given separator.
```js
// Lodash
var result = _.join(['one', 'two', 'three'], '--')
console.log(result)
// output: 'one--two--three'
// Native
var result = ['one', 'two', 'three'].join('--')
console.log(result)
// output: 'one--two--three'
```
#### Browser Support for `Array.prototype.join()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.last
Returns the last element of an array. Passing n will return the last n elements of the array.
```js
// Underscore/Lodash
const numbers = [1, 2, 3, 4, 5];
_.last(numbers);
// => 5
// Underscore
_.last(numbers, 2);
// => [4, 5]
// Native
const numbers = [1, 2, 3, 4, 5];
numbers[numbers.length - 1];
// => 5
//or
numbers.slice(-1)[0];
// => 5
//or
[].concat(numbers).pop()
// => 5
//or
numbers.at(-1);
// => 5
// Native (works even with potentially undefined/null)
[].concat(undefined).pop()
// => undefined
numbers.slice(-2);
// => [4, 5]
```
#### Browser Support for `Array.prototype.concat()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |
#### Browser Support for `Array.prototype.at()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
92 ✔ | 92 ✔ | 90 ✔ | ✖ | 78 ✔ | 15.4 ✔ |
**[⬆ back to top](#quick-links)**
### _.lastIndexOf
Returns the index of the last occurrence of value in the array, or -1 if value is not present.
```js
// Underscore/Lodash
var array = [2, 9, 9, 4, 3, 6]
var result = _.lastIndexOf(array, 9)
console.log(result)
// output: 2
// Native
var array = [2, 9, 9, 4, 3, 6]
var result = array.lastIndexOf(9)
console.log(result)
// output: 2
```
#### Browser Support for `Array.prototype.lastIndexOf()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.reverse
> [!IMPORTANT]
> Not in Underscore.js
Reverses array so that the first element becomes the last, the second element becomes the second to last, and so on.
```js
// Lodash
var array = [1, 2, 3]
console.log(_.reverse(array))
// output: [3, 2, 1]
// Native
var array = [1, 2, 3]
console.log(array.reverse())
// output: [3, 2, 1]
```
Voice from the Lodash author:
> Lodash's `_.reverse` just calls `Array#reverse` and enables composition like `_.map(arrays, _.reverse).`
> It's exposed on _ because previously, like `Underscore`, it was only exposed in the chaining syntax.
> --- [jdalton](https://github.com/cht8687/You-Dont-Need-Lodash-Underscore/commit/22c4bcf2be48dd415d2b073759805562e520b615#)
#### Browser Support for `Array.prototype.reverse()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.slice
Returns a shallow copy of a portion of an array into a new array object selected from `begin` to `end` (`end` not included)
```js
// Lodash
var array = [1, 2, 3, 4]
console.log(_.slice(array, 1, 3))
// output: [2, 3]
// Native
var array = [1, 2, 3, 4]
console.log(array.slice(1, 3));
// output: [2, 3]
```
#### Browser Support for `Array.prototype.slice()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.without
> [!IMPORTANT]
> Not in Underscore.js
Returns an array where matching items are filtered.
```js
// Lodash
var array = [1, 2, 3]
console.log(_.without(array, 2))
// output: [1, 3]
// Native
var array = [1, 2, 3]
console.log(array.filter(function(value) {
return value !== 2;
}));
// output: [1, 3]
```
#### Browser Support for `Array.prototype.filter()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.initial
Returns everything but the last entry of the array. Pass n to exclude the last n elements from the result.
```js
// Underscore
var array = [5, 4, 3, 2, 1]
console.log(_.initial(array, 2))
// output: [5, 4, 3]
// Native
var array = [5, 4, 3, 2, 1]
console.log(array.slice(0, -2));
// output: [5, 4, 3]
```
#### Browser Support for `Array.prototype.slice()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.pull
Removes all provided values from the given array using strict equality for comparisons, i.e. ===.
```js
// Lodash
const array = [1, 2, 3, 1, 2, 3];
_.pull(array, 2, 3);
console.log(array); // output: [1, 1]
```
```js
// Native JS
const array = [1, 2, 3, 1, 2, 3];
function pull(arr, ...removeList){
var removeSet = new Set(removeList)
return arr.filter(function(el){
return !removeSet.has(el)
})
}
console.log(pull(array, 2, 3)); // output: [1, 1]
console.log(array); // still [1, 2, 3, 1, 2, 3]. This is not in place, unlike lodash!
```
```ts
// TypeScript
const array = [1, 2, 3, 1, 2, 3];
const pull = <T extends unknown>(sourceArray: T[], ...removeList: T[]): T[] => {
const removeSet = new Set(removeList);
return sourceArray.filter(el => !removeSet.has(el));
};
console.log(pull(array, 2, 3)); // output: [1, 1]
console.log(array); // still [1, 2, 3, 1, 2, 3]. This is not in place, unlike lodash!
```
#### Browser Support for `Array.prototype.filter()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |
#### Browser Support for `Set.prototype.has()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
38 ✔ | 12 ✔ | 13 ✔ | 11 ✔ | 25 ✔ | 8 ✔ |
**[⬆ back to top](#quick-links)**
### _.unionBy
Creates an array of unique values, taking an `iteratee` to compute uniqueness with
(note that to iterate by a key in an object you must use `x => x.key` instead of `key` for the `iteratee`)
```js
// Lodash
var array1 = [2.1];
var array2 = [1.2, 2.3];
var result = _.unionBy(array1, array2, Math.floor)
console.log(result)
// output: [2.1, 1.2]
// Native
var array1 = [2.1];
var array2 = [1.2, 2.3];
function unionBy(...arrays) {
const iteratee = (arrays).pop();
if (Array.isArray(iteratee)) {
return []; // return empty if iteratee is missing
}
return [...arrays].flat().filter(
(set => (o) => set.has(iteratee(o)) ? false : set.add(iteratee(o)))(new Set()),
);
};
console.log(unionBy(array1, array2, Math.floor))
// output: [2.1, 1.2]
```
#### Browser Support for `Array.prototype.flat()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |
#### Browser Support for `Array.isArray()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 10.5 ✔ | 5.0 ✔ |
#### Browser Support for `Set.prototype.has()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
38 ✔ | 12 ✔ | 13 ✔ | 11 ✔ | 25 ✔ | 8 ✔ |
**[⬆ back to top](#quick-links)**
## Collection*
> [!IMPORTANT]
> Most native equivalents are array methods,
> and will not work with objects. If this functionality is needed and no object method is provided,
> then Lodash/Underscore is the better option.
### _.each
Iterates over a list of elements, yielding each in turn to an iteratee function.
```js
// Underscore/Lodash
//For arrays
_.each([1, 2, 3], function (value, index) {
console.log(value)
})
// output: 1 2 3
//For objects
_.each({'one':1, 'two':2, 'three':3}, function(value) {
console.log(value)
})
// output: 1 2 3
// Native
//For arrays
[1, 2, 3].forEach(function (value, index) {
console.log(value)
})
// output: 1 2 3
//For objects
Object.entries({'one':1, 'two':2, 'three':3}).forEach(function([key,value],index) {
console.log(value)
})
//output: 1 2 3
```
#### Browser Support for `Array.prototype.forEach()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
#### Browser Support for `Object.entries().forEach()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
54 ✔ | 14 ✔ | 47 ✔ | ✖ | 41 ✔ | 10.1✔ |
**[⬆ back to top](#quick-links)**
### _.every
Tests whether all elements in the array pass the test implemented by the provided function.
```js
// Underscore/Lodash
function isLargerThanTen (element, index, array) {
return element >= 10
}
var array = [10, 20, 30]
var result = _.every(array, isLargerThanTen)
console.log(result)
// output: true
// Native
function isLargerThanTen (element, index, array) {
return element >= 10
}
var array = [10, 20, 30]
var result = array.every(isLargerThanTen)
console.log(result)
// output: true
```
#### Browser Support for `Array.prototype.every()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.filter
Creates a new array with all elements that pass the test implemented by the provided function.
```js
// Underscore/Lodash
function isBigEnough (value) {
return value >= 10
}
var array = [12, 5, 8, 130, 44]
var filtered = _.filter(array, isBigEnough)
console.log(filtered)
// output: [12, 130, 44]
// Native
function isBigEnough (value) {
return value >= 10
}
var array = [12, 5, 8, 130, 44]
var filtered = array.filter(isBigEnough)
console.log(filtered)
// output: [12, 130, 44]
```
#### Browser Support for `Array.prototype.filter()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.groupBy
Group items by key.
```js
// Underscore/Lodash
var grouped = _.groupBy(['one', 'two', 'three'], 'length')
console.log(grouped)
// output: {3: ["one", "two"], 5: ["three"]}
// Native
var grouped = ['one', 'two', 'three'].reduce((r, v, i, a, k = v.length) => ((r[k] || (r[k] = [])).push(v), r), {})
console.log(grouped)
// output: {3: ["one", "two"], 5: ["three"]}
// Native
Object.groupBy(['one', 'two', 'three'], ({length}) => length)
// output: {3: ["one", "two"], 5: ["three"]}
```
```js
// Underscore/Lodash
var grouped = _.groupBy([1.3, 2.1, 2.4], num => Math.floor(num))
console.log(grouped)
// output: {1: [1.3], 2: [2.1, 2.4]}
// Native
var grouped = [1.3, 2.1, 2.4].reduce((r, v, i, a, k = Math.floor(v)) => ((r[k] || (r[k] = [])).push(v), r), {})
console.log(grouped)
// output: {1: [1.3], 2: [2.1, 2.4]}
// Native
Object.groupBy([1.3, 2.1, 2.4], num => Math.floor(num))
// output: {1: [1.3], 2: [2.1, 2.4]}
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
#### Browser Support for `Object.groupBy()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
117.0 ✔ | 117.0 ✔ | 119.0 ✔ | ✖ | 103.0 ✔ | 16.4 ✔ |
**[⬆ back to top](#quick-links)**
### _.includes
Checks if a value is in collection.
```js
var array = [1, 2, 3]
// Underscore/Lodash - also called _.contains
_.includes(array, 1)
// output: true
// Native
var array = [1, 2, 3]
array.includes(1)
// output: true
// Native (does not use same value zero)
var array = [1, 2, 3]
array.indexOf(1) > -1
// output: true
```
#### Browser Support for `Array.prototype.includes`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
47.0 ✔ | 14.0 ✔ | 43.0 ✔ | ✖ | 34.0 ✔ | 9.0 ✔ |
#### Browser Support for `Array.prototype.indexOf`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.keyBy
> [!WARNING]
> Not in Underscore.js
Creates an object composed of keys generated from the results of running each element of collection through iteratee.
```js
// Lodash
console.log(_.keyBy(['a', 'b', 'c']))
// output: { a: 'a', b: 'b', c: 'c' }
console.log(_.keyBy([{ id: 'a1', title: 'abc' }, { id: 'b2', title: 'def' }], 'id'))
// output: { a1: { id: 'a1', title: 'abc' }, b2: { id: 'b2', title: 'def' } }
console.log(_.keyBy({ data: { id: 'a1', title: 'abc' }}, 'id'))
// output: { a1: { id: 'a1', title: 'abc' }}
// keyBy for array only
const keyBy = (array, key) => (array || []).reduce((r, x) => ({ ...r, [key ? x[key] : x]: x }), {});
// Native
console.log(keyBy(['a', 'b', 'c']))
// output: { a: 'a', b: 'b', c: 'c' }
console.log(keyBy([{ id: 'a1', title: 'abc' }, { id: 'b2', title: 'def' }], 'id'))
// output: { a1: { id: 'a1', title: 'abc' }, b2: { id: 'b2', title: 'def' } }
console.log(keyBy(Object.values({ data: { id: 'a1', title: 'abc' }}), 'id'))
// output: { a1: { id: 'a1', title: 'abc' }}
// keyBy for array and object
const collectionKeyBy = (collection, key) => {
const c = collection || {};
return c.isArray() ? keyBy(c, key) : keyBy(Object.values(c), key);
}
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | 12.0 ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.map
Translates all items in an array or object to new array of items.
```js
// Underscore/Lodash
var array1 = [1, 2, 3]
var array2 = _.map(array1, function (value, index) {
return value * 2
})
console.log(array2)
// output: [2, 4, 6]
// Native
var array1 = [1, 2, 3]
var array2 = array1.map(function (value, index) {
return value * 2
})
console.log(array2)
// output: [2, 4, 6]
```
```js
// Underscore/Lodash
var object1 = { 'a': 1, 'b': 2, 'c': 3 }
var object2 = _.map(object1, function (value, index) {
return value * 2
})
console.log(object2)
// output: [2, 4, 6]
// Native
var object1 = { 'a': 1, 'b': 2, 'c': 3 }
var object2 = Object.entries(object1).map(function ([key, value], index) {
return value * 2
})
console.log(object2)
// output: [2, 4, 6]
```
#### Browser Support for `Object.entries()` and destructuring
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | ✖ | ✔ | ✔ |
#### Browser Support for `Array.prototype.map()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.minBy and _.maxBy
Use `Array.prototype.reduce()` for find the maximum or minimum collection item
```js
// Underscore/Lodash
var data = [{ value: 6 }, { value: 2 }, { value: 4 }]
var minItem = _.minBy(data, 'value')
var maxItem = _.maxBy(data, 'value')
console.log(minItem, maxItem)
// output: { value: 2 } { value: 6 }
// Native
var data = [{ value: 6 }, { value: 2 }, { value: 4 }]
var minItem = data.reduce(function(a, b) { return a.value <= b.value ? a : b }, {})
var maxItem = data.reduce(function(a, b) { return a.value >= b.value ? a : b }, {})
console.log(minItem, maxItem)
// output: { value: 2 }, { value: 6 }
```
Extract a functor and use es2015 for better code
```js
// utils
const makeSelect = (comparator) => (a, b) => comparator(a, b) ? a : b
const minByValue = makeSelect((a, b) => a.value <= b.value)
const maxByValue = makeSelect((a, b) => a.value >= b.value)
// main logic
const data = [{ value: 6 }, { value: 2 }, { value: 4 }]
const minItem = data.reduce(minByValue, {})
const maxItem = data.reduce(maxByValue, {})
console.log(minItem, maxItem)
// output: { value: 2 }, { value: 6 }
// or also more universal and little slower variant of minBy
const minBy = (collection, key) => {
// slower because need to create a lambda function for each call...
const select = (a, b) => a[key] <= b[key] ? a : b
return collection.reduce(select, {})
}
console.log(minBy(data, 'value'))
// output: { value: 2 }
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.pluck
`array.map` or `_.map` can also be used to replace `_.pluck`.
Lodash v4.0 removed `_.pluck` in favor of `_.map` with iteratee shorthand.
Details can be found in [Changelog](https://github.com/lodash/lodash/wiki/Changelog)
```js
// Underscore/Lodash
var array1 = [{name: "Alice"}, {name: "Bob"}, {name: "Jeremy"}]
var names = _.pluck(array1, "name")
console.log(names)
// output: ["Alice", "Bob", "Jeremy"]
// Native
var array1 = [{name: "Alice"}, {name: "Bob"}, {name: "Jeremy"}]
var names = array1.map(function(x){
return x.name
})
console.log(names)
// output: ["Alice", "Bob", "Jeremy"]
```
#### Browser Support for `Array.prototype.map()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.reduce
Applies a function against an accumulator and each value of the array (from left-to-right) to reduce it to a single value.
```js
// Underscore/Lodash
var array = [0, 1, 2, 3, 4]
var result = _.reduce(array, function (previousValue, currentValue, currentIndex, array) {
return previousValue + currentValue
})
console.log(result)
// output: 10
// Native
var array = [0, 1, 2, 3, 4]
var result = array.reduce(function (previousValue, currentValue, currentIndex, array) {
return previousValue + currentValue
})
console.log(result)
// output: 10
```
#### Browser Support for `Array.prototype.reduce()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.range
Creates an array of numbers progressing from start up to.
```js
// Underscore/Lodash
_.range(4) // output: [0, 1, 2, 3]
_.range(-4) // output: [0, -1, -2, -3]
_.range(1, 5) // output: [1, 2, 3, 4]
_.range(0, 20, 5) // output: [0, 5, 10, 15]
// Native ( solution with Array.from )
Array.from({length: 4}, (_, i) => i) // output: [0, 1, 2, 3]
Array.from({length: 4}, (_, i) => -i) // output: [-0, -1, -2, -3]
Array.from({length: 4}, (_, i) => i + 1) // output: [1, 2, 3, 4]
Array.from({length: 4}, (_, i) => i * 5) // output: [0, 5, 10, 15]
// Native ( solution with keys() and spread )
[...Array(4).keys()] // output: [0, 1, 2, 3]
[...Array(4).keys()].map(k => -k) // output: [-0, -1, -2, -3]
[...Array(4).keys()].map(k => k + 1) // output: [1, 2, 3, 4]
[...Array(4).keys()].map(k => k * 5) // output: [0, 5, 10, 15]
```
#### Browser Support for `Array.from()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 32.0 ✔ | ✖ | ✔ | 9.0 ✔ |
#### Browser Support for keys and spread in Array literals
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 7.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.reduceRight
This method is like _.reduce except that it iterates over elements of collection from right to left.
```js
// Underscore/Lodash
var array = [0, 1, 2, 3, 4]
var result = _.reduceRight(array, function (previousValue, currentValue, currentIndex, array) {
return previousValue - currentValue
})
console.log(result)
// output: -2
// Native
var array = [0, 1, 2, 3, 4]
var result = array.reduceRight(function (previousValue, currentValue, currentIndex, array) {
return previousValue - currentValue
})
console.log(result)
// output: -2
```
#### Browser Support for `Array.prototype.reduceRight()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.reject
The opposite of _.filter; this method returns the elements of collection that predicate does not return truthy for.
```js
// Underscore/Lodash
var array = [1, 2, 3, 4, 5];
var result = _.reject(array, function (x) {
return x % 2 === 0;
});
// output: [1, 3, 5]
// Native
var array = [1, 2, 3, 4, 5];
var reject = function (arr, predicate) {
var complement = function (f) {
return function (x) {
return !f(x);
}
};
return arr.filter(complement(predicate));
};
// output: [1, 3, 5]
```
#### Browser Support for `Array.prototype.filter()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | 12 ✔ | 1.5 ✔ | 9.0 ✔ | 9.5 ✔ | 3.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.sample
Gets a random element from `array`.
```js
// Underscore/Lodash
const array = [0, 1, 2, 3, 4]
const result = _.sample(array)
console.log(result)
// output: 2
// Native
const array = [0, 1, 2, 3, 4]
const sample = arr => {
const len = arr == null ? 0 : arr.length
return len ? arr[Math.floor(Math.random() * len)] : undefined
}
const result = sample(array)
console.log(result)
// output: 2
```
#### Browser Support for `Array.prototype.length()` and `Math.random()`
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:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.size
Returns the number of values in the collection.
```js
// Underscore/Lodash
var result = _.size({one: 1, two: 2, three: 3})
console.log(result)
// output: 3
// Native
var result2 = Object.keys({one: 1, two: 2, three: 3}).length
console.log(result2)
// output: 3
```
#### Browser Support for `Object.keys()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 12.0 ✔ | 5.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.some
Tests whether any of the elements in the array pass the test implemented by the provided function.
```js
// Underscore/Lodash
function isLargerThanTen (element, index, array) {
return element >= 10
}
var array = [10, 9, 8]
var result = _.some(array, isLargerThanTen)
console.log(result)
// output: true
// Native
function isLargerThanTen (element, index, array) {
return element >= 10
}
var array = [10, 9, 8]
var result = array.some(isLargerThanTen)
console.log(result)
// output: true
```
#### Browser Support for `Array.prototype.some()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | ✔ 9.0 | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.sortBy and _.orderBy
Sorts an array of object based on an object key provided by a parameter (note this is more limited than Underscore/Lodash).
```js
const fruits = [
{name:"banana", amount: 2},
{name:"apple", amount: 4},
{name:"pineapple", amount: 2},
{name:"mango", amount: 1}
];
// Underscore
_.sortBy(fruits, 'name');
// => [{name:"apple", amount: 4}, {name:"banana", amount: 2}, {name:"mango", amount: 1}, {name:"pineapple", amount: 2}]
// Lodash
_.orderBy(fruits, ['name'],['asc']);
// => [{name:"apple", amount: 4}, {name:"banana", amount: 2}, {name:"mango", amount: 1}, {name:"pineapple", amount: 2}]
// Native
const sortBy = (key) => {
return (a, b) => (a[key] > b[key]) ? 1 : ((b[key] > a[key]) ? -1 : 0);
};
// The native sort modifies the array in place. `_.orderBy` and `_.sortBy` do not, so we use `.concat()` to
// copy the array, then sort.
fruits.concat().sort(sortBy("name"));
// => [{name:"apple", amount: 4}, {name:"banana", amount: 2}, {name:"mango", amount: 1}, {name:"pineapple", amount: 2}]
```
#### Browser Support for `Array.prototype.concat()` and `Array.prototype.sort()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.uniq
Produces a duplicate-free version of the array, using === to test object equality.
```js
// Underscore/Lodash
var array = [1, 2, 1, 4, 1, 3]
var result = _.uniq(array)
console.log(result)
// output: [1, 2, 4, 3]
// Native
var array = [1, 2, 1, 4, 1, 3];
var result = [...new Set(array)];
console.log(result)
// output: [1, 2, 4, 3]
```
#### Browser Support for Spread in array literals
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |
**[⬆ back to top](#quick-links)**
## Function
### _.after
> [!WARNING]
> This is an alternative implementation
Creates a version of the function that will only be run after first being called count times. Useful for grouping asynchronous responses, where you want to be sure that all the async calls have finished, before proceeding.
```js
var notes = ['profile', 'settings']
// Underscore/Lodash
var renderNotes = _.after(notes.length, render)
notes.forEach(function (note) {
console.log(note)
renderNotes()
})
// Native
notes.forEach(function (note, index) {
console.log(note)
if (notes.length === (index + 1)) {
render()
}
})
```
#### Browser Support for `Array.prototype.forEach()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.bind
Create a new function that calls _func_ with _thisArg_ and _args_.
```js
var objA = {
x: 66,
offsetX: function(offset) {
return this.x + offset;
}
}
var objB = {
x: 67
};
// Underscore/Lodash
var boundOffsetX = _.bind(objA.offsetX, objB, 0);
// Native
var boundOffsetX = objA.offsetX.bind(objB, 0);
```
#### Browser Support for `Function.prototype.bind()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
7.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 11.6 ✔ | 5.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.isFunction
Checks if value is classified as a _Function_ object.
```js
// Lodash
_.isFunction(console.log);
// => true
_.isFunction(/abc/);
// => false
// Native
function isFunction(func) {
return typeof func === "function";
}
isFunction(setTimeout);
// => true
isFunction(123);
// => false
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.debounce
Create a new function that calls `func` with `thisArg` and `args`.
```js
function debounce(func, wait, immediate) {
var timeout;
return function() {
var context = this, args = arguments;
clearTimeout(timeout);
if (immediate && !timeout) func.apply(context, args);
timeout = setTimeout(function() {
timeout = null;
if (!immediate) func.apply(context, args);
}, wait);
};
}
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', debounce(calculateLayout, 150));
```
#### Browser Support for `debounce`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
7.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 11.6 ✔ | 5.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.partial
Create a new function that calls `func` with `args`.
```js
// Lodash
function greet(greeting, name) {
return greeting + ' ' + name;
}
var sayHelloTo = _.partial(greet, 'Hello');
var result = sayHelloTo('Jose')
console.log(result)
// output: 'Hello Jose'
// Native
function greet(greeting, name) {
return greeting + ' ' + name;
}
var sayHelloTo = (...args) => greet('Hello', ...args)
var result = sayHelloTo('Jose')
console.log(result)
// output: 'Hello Jose'
// Native
const partial = (func, ...boundArgs) => (...remainingArgs) => func(...boundArgs, ...remainingArgs)
var sayHelloTo = partial(greet, 'Hello');
var result = sayHelloTo('Jose')
console.log(result)
// output: 'Hello Jose'
```
#### Browser Support for Spread
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.throttle
Create a new function that limits calls to `func` to once every given timeframe.
```js
function throttle(func, timeFrame) {
var lastTime = 0;
return function (...args) {
var now = new Date();
if (now - lastTime >= timeFrame) {
func(...args);
lastTime = now;
}
};
}
// Avoid running the same function twice within the specified timeframe.
jQuery(window).on('resize', throttle(calculateLayout, 150));
```
#### Browser Support for `throttle`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | 12.0 ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |
**[⬆ back to top](#quick-links)**
## Lang
### _.castArray
Puts the value into an array of length one if it is not already an array.
```js
// Underscore
console.log(_.castArray(5))
// output: [5]
console.log(_.castArray([2]))
// output: [2]
// Native
function castArray(arr) {
return Array.isArray(arr) ? arr : [arr]
}
// output: true
console.log(castArray(5));
// output: [5]
console.log(castArray([2]));
// output: [2]
```
#### Browser Support for `Array.isArray()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 10.5 ✔ | 5.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.cloneDeep
Creates a deep copy by recursively cloning the value.
```js
// Lodash
var objects = [{ 'a': 1 }, { 'b': 2 }];
var clone = _.cloneDeep(objects);
console.log(clone[0] === objects[0]);
// output: false
// Native
var objects = [{ 'a': 1 }, { 'b': 2 }];
var clone = structuredClone(objects);
console.log(clone[0] === objects[0]);
// output: false
```
#### Browser Support for `structuredClone()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
98.0 ✔ | 98.0 ✔ | 94.0 ✔ | ✖ | 84.0 ✔ | 15.4 ✔ |
**[⬆ back to top](#quick-links)**
### _.isDate
Checks if value is classified as a Date object.
```js
// Lodash
console.log(_.isDate(new Date));
// output: true
// Native
console.log(Object.prototype.toString.call(new Date) === "[object Date]");
// output: true
```
#### Browser Support for `String.prototype.toString.call()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.gt
Checks if value is greater than other.
```js
// Lodash
console.log(_.gt(3, 1))
// output: true
// Native
console.log(3 > 1);
// output: true
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.gte
Checks if value is greater than or equal to other.
```js
// Lodash
console.log(_.gte(3, 1))
// output: true
// Native
console.log(3 >= 1);
// output: true
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.isEmpty
Checks if value is an empty object or collection.
> [!WARNING]
> The Native version does not support evaluating a Set or a Map
```js
// Lodash
console.log(_.isEmpty(null))
// output: true
console.log(_.isEmpty(''))
// output: true
console.log(_.isEmpty({}))
// output: true
console.log(_.isEmpty([]))
// output: true
console.log(_.isEmpty({a: '1'}))
// output: false
// Native
const isEmpty = obj => [Object, Array].includes((obj || {}).constructor) && !Object.entries((obj || {})).length;
console.log(isEmpty(null))
// output: true
console.log(isEmpty(''))
// output: true
console.log(isEmpty({}))
// output: true
console.log(isEmpty([]))
// output: true
console.log(isEmpty({a: '1'}))
// output: false
```
#### Browser Support for `Array.prototype.includes()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
47.0 ✔ | 14.0 ✔ | 43.0 ✔ | ✖ | 34.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.isFinite
Checks if value is a finite primitive number.
```js
// Lodash
console.log(_.isFinite('3'))
// output: false
console.log(_.isFinite(3))
// output: true
// Native
console.log(Number.isFinite('3'))
// output: false
console.log(Number.isFinite(3))
// output: true
```
#### Browser Support for `Number.isFinite()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
19.0 ✔ | ✔ | 16.0 ✔ | ✖ | 15.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.isInteger
Checks if value is an integer.
```js
// Lodash
console.log(_.isInteger(3))
// output: true
console.log(_.isInteger('3'))
// output: false
// Native
console.log(Number.isInteger(3))
// output: true
console.log(Number.isInteger('3'))
// output: false
```
#### Browser Support for `Number.isInteger()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | 12 ✔ | 16.0 ✔ | ✖ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.isPlainObject
Checks if value is a plain object, that is, an object created by the Object constructor or one with a [[Prototype]] of null.
```js
var object = { 'a': 1, 'b': 2, 'c': 1 };
// Underscore/Lodash
var result = _.isPlainObject(object);
console.log(result)
// output: true
function isPlainObject(value) {
if (typeof value !== 'object' || value === null) return false
if (Object.prototype.toString.call(value) !== '[object Object]') return false
const proto = Object.getPrototypeOf(value);
if (proto === null) return true
const Ctor = Object.prototype.hasOwnProperty.call(proto, 'constructor') && proto.constructor;
return (
typeof Ctor === 'function' &&
Ctor instanceof Ctor && Function.prototype.call(Ctor) === Function.prototype.call(value)
);
}
```
#### Browser Support for `Object.getPrototypeOf()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | 12.0 ✔ | 3.5 ✔ | ✖ | 12.1 ✔ | 5.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.isNaN
Checks if a value is NaN.
```js
// Underscore/Lodash
console.log(_.isNaN(NaN))
// output: true
// Native
console.log(isNaN(NaN))
// output: true
// ES6
console.log(Number.isNaN(NaN))
// output: true
```
MDN:
> In comparison to the global `isNaN()` function, `Number.isNaN()` doesn't suffer the problem of forcefully converting the parameter to a number. This means it is now safe to pass values that would normally convert to `NaN`, but aren't actually the same value as `NaN`. This also means that only values of the type number, that are also `NaN`, return true. [Number.isNaN()](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN)
Voice from the Lodash author:
> Lodash's `_.isNaN` is equiv to ES6 `Number.isNaN` which is different than the global `isNaN`.
> --- [jdalton](https://github.com/cht8687/You-Dont-Need-Lodash-Underscore/commit/b8559a603dccaaa2449b5a68a2d8325cf1fb29cd#)
#### Browser Support for `isNaN`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
#### Browser Support for `Number.isNaN`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
25.0 ✔ | ✔ | 15.0 ✔ | ✖ | ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.isNil
> [!WARNING]
> Not in Underscore.js
Checks if value is null or undefined.
```js
// Lodash
console.log(_.isNil(null))
// output: true
console.log(_.isNil(NaN))
// output: false
console.log(_.isNil(undefined))
// output: true
// Native
console.log(null == null);
// output: true
console.log(NaN == null);
// output: false
console.log(undefined == null)
// output: true
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.isNull
Checks if value is null.
```js
// Underscore/Lodash
console.log(_.isNull(null))
// output: true
console.log(_.isNull(void 0))
// output: false
// Native
console.log(null === null);
// output: true
console.log(void 0 === null);
// output: false
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.isUndefined
Checks if value is undefined.
```js
// Underscore/Lodash
console.log(_.isUndefined(a))
// output: true
// Native
console.log(typeof a === 'undefined');
// output: true
console.log(a === undefined);
// output: true
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
## Object
### _.assign
The method is used to copy the values of all enumerable own properties from one or more source objects to a target object.
```js
// Underscore: _.extendOwn
// Lodash
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
var result = _.assign(new Foo, new Bar);
console.log(result);
// output: { 'c': 3, 'e': 5 }
// Native
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
var result = Object.assign({}, new Foo, new Bar);
console.log(result);
// output: { 'c': 3, 'e': 5 }
```
#### Browser Support for `Object.assign()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 34.0 ✔ | ✖ | 32.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.defaults
The method is used to apply new values over an object with default values for keys.
```js
// Underscore: _.defaults
// Lodash
const newValues = {a: 3};
const defaultValues = {a: 1, b: 2}
const appliedValues = _.defaults(newValues, defaultValues);
console.log(appliedValues)
// output { a: 3, b: 2 }
// Native
const newValues = {a: 3};
const defaultValues = {a: 1, b: 2}
const appliedValues = Object.assign({}, defaultValues, newValues);
// output { a: 3, b: 2 }
```
#### Browser Support for `Object.assign()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 34.0 ✔ | ✖ | 32.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.extend
The method is used to copy the values of all enumerable own and inherited properties from one or more source objects to a target object.
```js
// Underscore
// Lodash: _.assignIn
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
var result = _.extend({}, new Foo, new Bar);
console.log(result);
// output: { 'c': 3, 'd': 4, 'e': 5, 'f': 6 }
// Native
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
var result = Object.assign({}, new Foo, Foo.prototype, new Bar, Bar.prototype);
console.log(result);
// output: { 'c': 3, 'd': 4, 'e': 5, 'f': 6 }
//Or using a function
const extend = (target, ...sources) => {
const length = sources.length;
if (length < 1 || target == null) return target;
for (let i = 0; i < length; i++) {
const source = sources[i];
for (const key in source) {
target[key] = source[key];
}
}
return target;
};
console.log(extend({}, new Foo, new Bar));
// output: { 'c': 3, 'd': 4, 'e': 5, 'f': 6 }
```
#### Browser Support for `Object.assign()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 34.0 ✔ | ✖ | 32.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.has
Checks if `key` is a direct property of `object`. Key may be a path of a value separated by `.`
```js
// Lodash
var object = { a: 1, b: 'settings', c: { d: 'test' } };
var hasA = _.has(object, 'a');
var hasCWhichHasD = _.has(object, 'c.d')
console.log(hasA);
// output: true
console.log(hasCWhichHasD);
// output: true
// Native
const has = function (obj, key) {
var keyParts = key.split('.');
return !!obj && (
keyParts.length > 1
? has(obj[key.split('.')[0]], keyParts.slice(1).join('.'))
: hasOwnProperty.call(obj, key)
);
};
var object = { a: 1, b: 'settings' };
var result = has(object, 'a');
// output: true
```
#### Browser Support for Object .hasOwnProperty
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | 12 ✔ | ✔ | 5.5 ✔ | 5 ✔ | 3 ✔ |
**[⬆ back to top](#quick-links)**
### _.get
Gets the value at path of object.
> [!NOTE]
> If provided path does not exist inside the object js will generate error.
```js
// Lodash
var object = { a: [{ b: { c: 3 } }] };
var result = _.get(object, 'a[0].b.c', 1);
console.log(result);
// output: 3
// Native (ES6 - IE not supported)
var object = { a: [{ b: { c: 3 } }] };
var { a: [{ b: { c: result = 1 } = {} } = {}] = [] } = object;
console.log(result);
// output: 3
// Native (ES11)
var object = { a: [{ b: { c: 3 } }] };
var result = object?.a?.[0]?.b?.c ?? 1;
console.log(result);
// output: 3
// Native
const get = (obj, path, defaultValue = undefined) => {
const travel = regexp =>
String.prototype.split
.call(path, regexp)
.filter(Boolean)
.reduce((res, key) => (res !== null && res !== undefined ? res[key] : res), obj);
const result = travel(/[,[\]]+?/) || travel(/[,[\].]+?/);
return result === undefined || result === obj ? defaultValue : result;
};
var object = { a: [{ b: { c: 3 } }] };
var result = get(object, 'a[0].b.c', 1);
// output: 3
```
#### Browser Support for Object destructing
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
49.0 ✔ | 14.0 ✔ | 41.0 ✔ | ✖ | 41.0 ✔ | 8.0 ✔ |
#### Browser Support for optional chaining `?.`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
80.0 ✔ | 80.0 ✔ | 74.0 ✔ | ✖ | 67.0 ✔ | 13.1 ✔ |
#### Browser Support for nullish coalescing operator `??`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
80.0 ✔ | 80.0 ✔ | 72.0 ✔ | ✖ | ✖ | 13.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.invert
Creates an object composed of the inverted keys and values of object. If object contains duplicate values, subsequent values overwrite property assignments of previous values.
```js
var object = { 'a': 1, 'b': 2, 'c': 1 };
// Underscore/Lodash
var result = _.invert(object);
console.log(result)
// output: { '1': 'c', '2': 'b' }
// Native (IE6)
function invert(object) {
var obj = {};
for (var key in object) {
if (object.hasOwnProperty(key)) {
obj[object[key]] = key;
}
}
return obj;
}
var result = invert(object);
console.log(result)
// output: { '1': 'c', '2': 'b' }
// Native (IE not supported)
const invert = object => Object.entries(object)
.reduce((acc, current) => {
acc[current[1]] = current[0];
return acc;
}, {}
);
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
4.0 ✔ | ✔ | 2.0 ✔ | 6.0 ✔ | 10.0 ✔ | 3.1 ✔ |
#### Browser Support for `Object.entries()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
54.0 ✔ | 14.0 ✔ | 47.0 ✔ | ✖ | 41.0 ✔ | 10.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.keys
Retrieves all the names of the object's own enumerable properties.
```js
// Underscore/Lodash
var result = _.keys({one: 1, two: 2, three: 3})
console.log(result)
// output: ["one", "two", "three"]
// Native
var result2 = Object.keys({one: 1, two: 2, three: 3})
console.log(result2)
// output: ["one", "two", "three"]
```
#### Browser Support for `Object.keys()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 12.0 ✔ | 5.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.mapKeys
The opposite of _.mapValues; this method creates an object with the same values as object and keys generated by running each own enumerable string keyed property of object thru iteratee. The iteratee is invoked with three arguments: (value, key, object).
```js
// Lodash
var result = _.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
return key + value;
});
console.log(result)
// output: { 'a1': 1, 'b2': 2 }
// Native (IE6)
function mapKeys(object, cb) {
var obj = {};
for (var key in object) {
if (object.hasOwnProperty(key)) {
var newKey = cb(object[key], key, object);
obj[newKey] = object[key];
}
}
return obj;
}
var result = mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
return key + value;
});
console.log(result)
// output: { 'a1': 1, 'b2': 2 }
// Native (IE not supported)
const mapKeys = (object, cb) => Object.entries(object)
.reduce((acc, current) => {
const newKey = cb(current[1], current[0], object);
acc[newKey] = current[1];
return acc;
}, {}
);
const result2 = mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
return key + value;
});
console.log(result2)
// output: { 'a1': 1, 'b2': 2 }
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
4.0 ✔ | ✔ | 2.0 ✔ | 6.0 ✔ | 10.0 ✔ | 3.1 ✔ |
#### Browser Support for `Object.entries()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
54.0 ✔ | 14.0 ✔ | 47.0 ✔ | ✖ | 41.0 ✔ | 10.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.omit
Returns a copy of the object, filtered to omit the keys specified.
```js
var object = { 'a': 1, 'b': '2', 'c': 3 };
// Underscore/Lodash
var result = _.omit(object, ['a', 'c']);
console.log(result)
// output: { 'b': '2' }
// Native
var { a, c, ...result2 } = object;
console.log(result2)
// output: { 'b': '2' }
```
#### Browser Support for Spread in object literals
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
60.0 ✔ | 79 ✔ | 55.0 ✔ | ✖ | 37.0 ✔ | ✖ |
**[⬆ back to top](#quick-links)**
### _.pick
Creates an object composed of the object properties predicate returns truthy for.
```js
var object = { 'a': 1, 'b': '2', 'c': 3 };
// Underscore/Lodash
var result = _.pick(object, ['a', 'c', 'x']);
console.log(result)
// output: {a: 1, c: 3}
// Native
function pick(object, keys) {
return keys.reduce((obj, key) => {
if (object && object.hasOwnProperty(key)) {
obj[key] = object[key];
}
return obj;
}, {});
}
var result = pick(object, ['a', 'c', 'x']);
console.log(result)
// output: {a: 1, c: 3}
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
38.0 ✔ | ✔ | 13.0 ✔ | 12.0 ✔ | 25.0 ✔ | 7.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.pickBy
Creates an object composed of the object properties predicate returns truthy for.
```js
var object = { 'a': 1, 'b': null, 'c': 3, 'd': false, 'e': undefined };
// Underscore/Lodash
var result = _.pickBy(object);
console.log(result)
// output: {a: 1, c: 3}
// Native
function pickBy(object) {
const obj = {};
for (const key in object) {
if (object[key]) {
obj[key] = object[key];
}
}
return obj;
}
var result = pickBy(object);
console.log(result)
// output: {a: 1, c: 3}
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | 6.0 ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.toPairs
Retrieves all the given object's own enumerable property `[ key, value ]` pairs.
```js
// Underscore - also called _.pairs
// Lodash - also called _.entries
var result = _.toPairs({one: 1, two: 2, three: 3})
console.log(result)
// output: [["one", 1], ["two", 2], ["three", 3]]
// Native
var result2 = Object.entries({one: 1, two: 2, three: 3})
console.log(result2)
// output: [["one", 1], ["two", 2], ["three", 3]]
```
#### Browser Support for `Object.entries()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
54.0 ✔ | 14.0 ✔ | 47.0 ✔ | ✖ | 41.0 ✔ | 10.1 ✔ |
**[⬆ back to top](#quick-links)**
### _.values
Retrieves all the given object's own enumerable property values.
```js
// Underscore/Lodash
var result = _.values({one: 1, two: 2, three: 3})
console.log(result)
// output: [1, 2, 3]
// Native
var result2 = Object.values({one: 1, two: 2, three: 3})
console.log(result2)
// output: [1, 2, 3]
```
#### Browser Support for `Object.values()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
54.0 ✔ | 14.0 ✔ | 47.0 ✔ | ✖ | 41.0 ✔ | 10.1 ✔ |
**[⬆ back to top](#quick-links)**
## String
### _.capitalize
> [!WARNING]
> Not in Underscore.js
Converts the first character of string to upper case and the remaining to lower case.
```js
// Lodash
var result = _.capitalize('FRED');
console.log(result);
// => 'Fred'
// Native
const capitalize = (string) => {
return string ? string.charAt(0).toUpperCase() + string.slice(1).toLowerCase() : '';
};
var result = capitalize('FRED');
console.log(result);
// => 'Fred'
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.endsWith
> [!WARNING]
> Not in Underscore.js
Checks if string ends with the given target string.
```js
// Lodash
_.endsWith('abc', 'c');
// => true
_.endsWith('abc', 'b');
// => false
_.endsWith('abc', 'b', 2);
// => true
// Native
'abc'.endsWith('c');
// => true
'abc'.endsWith('b');
// => false
'abc'.endsWith('b', 2);
// => true
```
#### Browser Support for `String.prototype.endsWith()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
41.0 ✔ | ✔ | 17.0 ✔ | ✖ | 28.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.isString
Checks if value is classified as a String primitive or object.
```js
// Lodash
_.isString('abc');
// => true
_.isString(123);
// => false
// Native
function isString(str){
if (str != null && typeof str.valueOf() === "string") {
return true
}
return false
}
isString('abc');
// => true
isString(123);
// => false
```
#### Browser Support
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.lowerFirst
> [!WARNING]
> Not in Underscore.js
Converts the first character of string to lower case.
```js
// Lodash
var result = _.lowerFirst('Fred')
console.log(result)
// output: 'fred'
// Native
const lowerFirst = (string) => {
return string ? string.charAt(0).toLowerCase() + string.slice(1) : ''
}
var result = lowerFirst('Fred')
console.log(result)
// output: 'fred'
```
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.padStart and _.padEnd
> [!WARNING]
> Not in Underscore.js
Pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length.
```js
// Lodash
console.log(_.padStart('123', 5, '0'))
// output: '00123'
console.log(_.padEnd('123', 5, '0'))
// output: '12300'
// Native
console.log('123'.padStart(5, '0'))
// output: '00123'
console.log('123'.padEnd(5, '0'))
// output: '12300'
```
#### Browser Support for `String.prototype.padStart()` and `String.prototype.padEnd()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
57.0 ✔ | 15.0 ✔ | 48.0 ✔ | ✖ | 44.0 ✔ | 10.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.repeat
> [!WARNING]
> Not in Underscore.js
Repeats the given string n times.
```js
// Lodash
var result = _.repeat('abc', 2)
console.log(result)
// output: 'abcabc'
// Native
var result = 'abc'.repeat(2)
console.log(result)
// output: 'abcabc'
```
#### Browser Support for `String.prototype.repeat()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
41.0 ✔ | ✔ | 24.0 ✔ | ✖ | 28.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.replace
Returns a new string with some or all matches of a `pattern` replaced by a `replacement`.
```js
// Lodash
var re = /apples/gi;
var str = 'Apples are round, and apples are juicy.';
var newstr = _.replace(str, re, 'oranges');
console.log(newstr);
// output: 'oranges are round, and oranges are juicy.'
// Native
var re = /apples/gi;
var str = 'Apples are round, and apples are juicy.';
var result = str.replace(re, 'oranges');
console.log(result);
// output: 'oranges are round, and oranges are juicy.'
```
#### Browser Support for `String.prototype.replace()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.split
> [!WARNING]
> Not in Underscore.js
Splits string by separator.
```js
// Lodash
var result = _.split('a-b-c', '-', 2)
console.log(result)
// output: ['a','b']
// Native
var result = 'a-b-c'.split('-', 2)
console.log(result)
// output: ['a','b']
```
#### Browser Support for `String.prototype.split()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.startsWith
> [!WARNING]
> Not in Underscore.js
Checks if string starts with the given target string.
```js
// Lodash
var result = _.startsWith('abc', 'b', 1)
console.log(result)
// output: true
// Native
var result = 'abc'.startsWith('b', 1)
console.log(result)
// output: true
```
#### Browser Support for `String.prototype.startsWith()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
41.0 ✔ | ✔ | 17.0 ✔ | ✖ | 28.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.template
> [!NOTE]
> This is an alternative implementation. Native template literals not escape html.
Create a template function.
```js
// Lodash/Underscore
const compiled = _.template('hello <%= user %>!');
var result = compiled({ 'user': 'fred' });
console.log(result);
// output: 'hello fred'
// Native
const templateLiteral = (value) => `hello ${value.user}`;
var result = templateLiteral({ 'user': 'fred' });
console.log(result);
// output: 'hello fred'
```
#### Browser Support for String (template) literals
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
41.0 ✔ | 12.0 ✔ | 34.0 ✔ | ✖ | 28.0 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.toLower
> [!WARNING]
> Not in Underscore.js
Lowercases a given string.
```js
// Lodash
var result = _.toLower('FOOBAR')
console.log(result)
// output: 'foobar'
// Native
var result = 'FOOBAR'.toLowerCase()
console.log(result)
// output: 'foobar'
```
#### Browser Support for `String.prototype.toLowerCase()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.toUpper
> [!WARNING]
> Not in Underscore.js
Uppercases a given string.
```js
// Lodash
var result = _.toUpper('foobar')
console.log(result)
// output: 'FOOBAR'
// Native
var result = 'foobar'.toUpperCase()
console.log(result)
// output: 'FOOBAR'
```
#### Browser Support for `String.prototype.toUpperCase()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.trim
> [!WARNING]
> Not in Underscore.js
Removes the leading and trailing whitespace characters from a string.
```js
// Lodash
var result = _.trim(' abc ')
console.log(result)
// output: 'abc'
// Native
var result = ' abc '.trim()
console.log(result)
// output: 'abc'
```
#### Browser Support for `String.prototype.trim()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 3.5 ✔ | 9.0 ✔ | 10.5 ✔ | 5.0 ✔ |
**[⬆ back to top](#quick-links)**
### _.upperFirst
> [!WARNING]
> Not in Underscore.js
Uppercases the first letter of a given string.
```js
// Lodash
var result = _.upperFirst('george')
console.log(result)
// output: 'George'
// Native
const upperFirst = (string) => {
return string ? string.charAt(0).toUpperCase() + string.slice(1) : ''
}
var result = upperFirst('george')
console.log(result)
// output: 'George'
```
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
## Reference
* [Mozilla Developer Network](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference)
* [Underscore.js](http://underscorejs.org)
* [Lodash.js](https://lodash.com/docs)
**[⬆ back to top](#quick-links)**
### _.uniqWith
Similar to `_.uniq` except that it accepts comparator which is invoked to compare elements of array. The order of result values is determined by the order they occur in the array.
```js
// Lodash
const objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];
const result = _.uniqWith(objects, _.isEqual);
console.log(result);
// output: [{ x: 1, y: 2 }, { x: 2, y: 1 }]
// Native
const uniqWith = (arr, fn) => arr.filter((element, index) => arr.findIndex((step) => fn(element, step)) === index);
const array = [1, 2, 2, 3, 4, 5, 2];
const result = uniqWith(array, (a, b) => a === b);
console.log(result);
// output: [1, 2, 3, 4, 5]
const objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];
const result = uniqWith(objects, (a, b) => JSON.stringify(a) === JSON.stringify(b));
console.log(result);
// output: [{ x: 1, y: 2 }, { x: 2, y: 1 }]
```
### Browser Support for `Array.prototype.filter()` and `Array.prototype.findIndex()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | 12.0 ✔ | 25.0 ✔ | ✖ | 32.0 ✔ | 8.0 ✔ |
**[⬆ back to top](#quick-links)**
## Util
### _.times
Invokes the iteratee n times, returning an array of the results of each invocation.
```js
// Lodash
var result = _.times(10)
console.log(result)
// output: '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]'
// Native
var result = Array.from({length: 10}, (_,x) => x)
console.log(result)
// output: '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]'
// Native
var result = [...Array(10).keys()]
console.log(result)
// output: '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]'
```
#### Browser Support for `Array.from()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 32.0 ✔ | ✖ | ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
## Number
### _.clamp
Clamps number within the inclusive lower and upper bounds.
```js
// Lodash
_.clamp(-10, -5, 5);
// => -5
_.clamp(10, -5, 5);
// => 5
_.clamp(10, -5);
// => -5
_.clamp(10, 99);
// => 10
// Native
const clamp = (number, boundOne, boundTwo) => {
if (!boundTwo) {
return Math.max(number, boundOne) === boundOne ? number : boundOne;
} else if (Math.min(number, boundOne) === number) {
return boundOne;
} else if (Math.max(number, boundTwo) === number) {
return boundTwo;
}
return number;
};
clamp(-10, -5, 5);
// => -5
clamp(10, -5, 5);
// => 5
clamp(10, -5);
// => -5
clamp(10, 99);
// => 10
```
#### Browser Support for `Math.min() and Math.max()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.inRange
Checks if n is between start and up to, but not including, end. If end is not specified, it's set to start with start then set to 0. If start is greater than end the params are swapped to support negative ranges.
```js
// Lodash
_.inRange(3, 2, 4);
// output: true
_.inRange(-3, -2, -6);
// output: true
//Native
const inRange = (num, init, final) => {
if(final === undefined){
final = init;
init = 0;
}
return (num >= Math.min(init, final) && num < Math.max(init, final));
}
//Native
const inRange = (num, a, b=0) => (Math.min(a,b) <= num && num < Math.max(a,b));
inRange(3, 2, 4);
// output: true
inRange(-3, -2, -6);
// output: true
```
#### Browser Support for `Math.min() and Math.max()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
### _.random
Produces a random number between the inclusive lower and upper bounds. If only one argument is provided a number between 0 and the given number is returned. If floating is true, or either lower or upper are floats, a floating-point number is returned instead of an integer.
```js
// Lodash
_.random(0, 5);
// => an integer between 0 and 5
_.random(5);
// => also an integer between 0 and 5
_.random(5, true);
// => a floating-point number between 0 and 5
_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2
//Native ES6
const random = (a = 1, b = 0) => {
const lower = Math.min(a, b);
const upper = Math.max(a, b);
return lower + Math.random() * (upper - lower);
};
const randomInt = (a = 1, b = 0) => {
const lower = Math.ceil(Math.min(a, b));
const upper = Math.floor(Math.max(a, b));
return Math.floor(lower + Math.random() * (upper - lower + 1))
};
random();
// => a floating-point number between 0 and 1
random(5);
// => a floating-point number between 0 and 5
random(0, 5);
// => also a floating-point number between 0 and 5
random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2
randomInt();
// => just 0 or 1
randomInt(5);
// => an integer between 0 and 5
randomInt(0, 5);
// => also an integer between 0 and 5
randomInt(1.2, 5.2);
// => an integer between 2 and 5
```
#### Browser Support for `Math.random()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
**[⬆ back to top](#quick-links)**
## Inspired by:
* [You-Dont-Need-jQuery](https://github.com/oneuijs/You-Dont-Need-jQuery)
* [Rui's blog](http://ktei.github.io/2016/01/07/some-general-js-tips-1.html)
## License
MIT
[chrome-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/chrome/chrome_48x48.png
[firefox-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/firefox/firefox_48x48.png
[ie-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/archive/internet-explorer_9-11/internet-explorer_9-11_48x48.png
[opera-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/opera/opera_48x48.png
[safari-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/safari/safari_48x48.png
[edge-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/edge/edge_48x48.png
================================================
FILE: TEMPLATE.md
================================================
## Quick Links
**[Section](#section)**
1. [_.sortYourMethodAlphabetically](#_sortYourMethodAlphabetically)
### _.sortYourMethodAlphabetically
Explains or copy/paste lodash/underscore description.
```js
// Lodash
var result = _.sortYourMethodAlphabetically('abc', ...)
console.log(result)
// output: true
// Native
var result = 'abc'.sortYourMethodAlphabetically(...)
console.log(result)
// output: true
```
#### Browser Support for `Array.prototype.sortYourMethodAlphabetically()`
![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
41.0 ✔ | 15.0 ✔ | 17.0 ✔ | ✖ | 10.5 ✔ | 9.0 ✔ |
**[⬆ back to top](#quick-links)**
> !------ DO NOT COPY THESE LINES BELOW -------------!
> For Browser support, visit [MDN web docs](https://developer.mozilla.org/en-US/), search for a term there and see the bottom section of the page.
[chrome-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/chrome/chrome_48x48.png
[firefox-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/firefox/firefox_48x48.png
[ie-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/archive/internet-explorer_9-11/internet-explorer_9-11_48x48.png
[opera-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/opera/opera_48x48.png
[safari-image]: https://raw.githubusercontent.com/alrra/browser-logos/master/src/safari/safari_48x48.png
[edge-image]:
https://raw.githubusercontent.com/alrra/browser-logos/master/src/edge/edge_48x48.png
================================================
FILE: configuring.md
================================================
## Configuring the ESLint Plugin
### If you haven't already, add ESLint to your project
```sh
npm install --save-dev eslint
```
### Add the plugin
```sh
npm install --save-dev eslint-plugin-you-dont-need-lodash-underscore
```
### Add the plugin to your .eslintrc.js file
```js
"plugins": ["you-dont-need-lodash-underscore"],
```
If you already have plugins installed, just add to the array.
```js
"plugins": ["react", "you-dont-need-lodash-underscore"],
```
### Now configure your plugin.
You can enable or disable individual rules.
```js
"rules": {
"you-dont-need-lodash-underscore/for-each": "error",
"you-dont-need-lodash-underscore/concat": "warn",
"you-dont-need-lodash-underscore/map": "off",
...
}
```
To save the trouble of configuring each rule individually, you can start by extending one of the
default configurations, and then override individual rules as desired.
```js
"extends" : ["plugin:you-dont-need-lodash-underscore/compatible"],
```
The following options are available:
- you-dont-need-lodash-underscore:all-warn (all rules set to warn)
- you-dont-need-lodash-underscore:all (all rules set to error)
- you-dont-need-lodash-underscore:compatible-warn (rules in which the native implementation is perfectly compatible with the _ one are set to warn, the rest are disabled)
- you-dont-need-lodash-underscore:compatible (rules in which the native implementation is perfectly compatible with _ one are set to error, the rest are set to warn)
For more information, see the [ESLint documentation](http://eslint.org/docs/user-guide/configuring).
================================================
FILE: docs/.nojekyll
================================================
================================================
FILE: docs/README.md
================================================
[remoteMarkdownUrl](https://raw.githubusercontent.com/you-dont-need/You-Dont-Need-Lodash-Underscore/master/README.md)
================================================
FILE: docs/index.html
================================================
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>You don’t (may not) need Lodash/Underscore</title>
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
<meta name="description" content="Description">
<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<link rel="stylesheet" href="//cdn.jsdelivr.net/npm/docsify/lib/themes/vue.css">
</head>
<body>
<div id="app"></div>
<script>
window.$docsify = {
name: 'You don\'t need Lodash',
nameLink: '/',
repo: 'https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore',
autoHeader: true,
maxLevel: 3,
markdown: {
smartypants: true
},
remoteMarkdown: {
tag: 'remoteMarkdownUrl',
},
}
</script>
<script src="//cdn.jsdelivr.net/npm/docsify/lib/docsify.min.js"></script>
<script src="//unpkg.com/docsify-remote-markdown/dist/docsify-remote-markdown.min.js"></script>
<script src="//cdn.jsdelivr.net/npm/prismjs@1/components/prism-js-extras.min.js"></script>
<script src="//cdn.jsdelivr.net/npm/prismjs@1/components/prism-js-templates.min.js"></script>
<script src="//cdn.jsdelivr.net/npm/prismjs@1/components/prism-jsdoc.min.js"></script>
</body>
</html>
================================================
FILE: index.js
================================================
'use strict';
const kebabCase = require('kebab-case');
const rules = require('./lib/rules/rules.json')
module.exports.rules = require('./lib/rules/all');
const all = Object.keys(rules);
const compatible = Object.keys(rules).filter(rule => rules[rule].compatible);
const incompatible = Object.keys(rules).filter(rule => !rules[rule].compatible);
const WARN = 1;
const ERROR = 2;
const configure = (list, level) => (
list.reduce((ret, rule) => (Object.assign({}, ret,
{ ['you-dont-need-lodash-underscore/' + (rules[rule].ruleName || kebabCase(rule))]: level })), {})
)
module.exports.configs = {
'all-warn': {
plugins: [
'you-dont-need-lodash-underscore'
],
rules: configure(all, WARN)
},
'all': {
plugins: [
'you-dont-need-lodash-underscore'
],
rules: configure(all, ERROR)
},
'compatible-warn': {
plugins: [
'you-dont-need-lodash-underscore'
],
rules: configure(compatible, WARN)
},
'compatible': {
plugins: [
'you-dont-need-lodash-underscore'
],
rules: Object.assign(
configure(compatible, ERROR),
configure(incompatible, WARN)
)
}
}
================================================
FILE: lib/rules/all.js
================================================
'use strict';
const kebabCase = require('kebab-case');
const rules = require('./rules');
const forbiddenLibs = ['lodash', 'lodash/fp', 'lodash-es'];
function getAssignmentLeftHandSide(node) {
// For VariableDeclarator nodes, the left hand side is called `id`
// The `x` on `var x = 3;
if (node.type === 'VariableDeclarator') {
return node.id;
}
// For AssignmentExpression nodes, the left hand side is called `left`
// The `x` on `x = 3;
if (node.type === 'AssignmentExpression') {
return node.left;
}
return null;
}
for (const rule in rules) {
const alternative = rules[rule].alternative;
const ruleName = rules[rule].ruleName || kebabCase(rule);
const forbiddenImports = {
[`lodash/${rule}`]: 1,
[`lodash/fp/${rule}`]: 1,
[`lodash-es/${rule}`]: 1,
[`lodash.${rule.toLowerCase()}`]: 1,
};
module.exports[ruleName] = {
create(context) {
return {
CallExpression(node) {
const callee = node.callee;
const objectName = callee.name || (callee.object && callee.object.name) || (callee.object && callee.object.callee && callee.object.callee.name);
if (objectName === 'require' && node.arguments.length === 1) {
const requiredModuleName = node.arguments[0].value;
const { parent } = node;
if (forbiddenLibs.includes(requiredModuleName)) {
const leftHandSide = getAssignmentLeftHandSide(parent);
// ex: const { indexOf } = require('lodash');
// ex: ({ indexOf } = require('lodash'));
if (leftHandSide && leftHandSide.type === 'ObjectPattern') {
leftHandSide.properties.forEach(property => {
if (property.key.name === rule) {
context.report({
node,
message: `{ ${rule} } = require('${requiredModuleName}') detected. Consider using the native ${alternative}`
});
}
});
}
} else if (forbiddenImports.hasOwnProperty(requiredModuleName)) {
// ex: const indexOf = require('lodash.indexof');
// ex: const indexOf = require('lodash/indexOf');
context.report({
node,
message: `require('${requiredModuleName}') detected. Consider using the native ${alternative}`
});
}
} else if ((objectName === '_' || objectName === 'lodash' || objectName === 'underscore') && callee.property && callee.property.name === rule) {
context.report({
node,
message: `Consider using the native ${alternative}`
});
}
},
ImportDeclaration(node) {
if (forbiddenLibs.includes(node.source.value)) {
// ex: import { indexOf } from 'lodash';
// ex: import { indexOf as x } from 'lodash';
node.specifiers.forEach(specifier => {
if (specifier.type === 'ImportSpecifier' && specifier.imported.name === rule) {
context.report({
node,
message: `Import { ${rule} } from '${node.source.value}' detected. Consider using the native ${alternative}`
});
}
});
} else if (forbiddenImports.hasOwnProperty(node.source.value)) {
// ex: import indexOf from 'lodash/indexOf';
// ex: import indexOf from 'lodash.indexof';
context.report({
node,
message: `Import from '${node.source.value}' detected. Consider using the native ${alternative}`
});
}
}
};
}
};
}
================================================
FILE: lib/rules/rules.json
================================================
{
"concat": {
"compatible": true,
"alternative": "Array.prototype.concat()"
},
"drop": {
"compatible": true,
"alternative": "Array.prototype.slice()"
},
"dropRight": {
"compatible": true,
"alternative": "Array.prototype.slice()"
},
"indexOf": {
"compatible": true,
"alternative": "Array.prototype.indexOf()"
},
"join": {
"compatible": true,
"alternative": "Array.prototype.join()"
},
"last": {
"compatible": true,
"alternative": "Array.prototype.at(-1) or Array.prototype.slice()",
"ES13": true
},
"lastIndexOf": {
"compatible": true,
"alternative": "Array.prototype.lastIndexOf()"
},
"reverse": {
"compatible": true,
"alternative": "Array.prototype.reverse()"
},
"fill": {
"compatible": true,
"alternative": "Array.prototype.fill()",
"ES6": true
},
"find": {
"compatible": false,
"alternative": "Array.prototype.find()",
"ES6": true
},
"detect": {
"compatible": true,
"alternative": "Array.prototype.find()",
"ES6": true
},
"first": {
"compatible": true,
"alternative": "Array.prototype.at(0) or Array.prototype.slice()",
"ES13": true
},
"findIndex": {
"compatible": false,
"alternative": "Array.prototype.findIndex()",
"ES6": true
},
"isArray": {
"compatible": true,
"alternative": "Array.isArray()"
},
"each": {
"compatible": false,
"alternative": "Array.prototype.forEach() or Object.entries().forEach()"
},
"forEach": {
"compatible": false,
"alternative": "Array.prototype.forEach() or Object.entries().forEach()"
},
"every": {
"compatible": false,
"alternative": "Array.prototype.every()"
},
"all": {
"compatible": false,
"alternative": "Array.prototype.every()"
},
"filter": {
"compatible": false,
"alternative": "Array.prototype.filter()"
},
"select": {
"compatible": false,
"alternative": "Array.prototype.filter()"
},
"map": {
"compatible": false,
"alternative": "Array.prototype.map()"
},
"collect": {
"compatible": false,
"alternative": "Array.prototype.map()"
},
"reduce": {
"compatible": false,
"alternative": "Array.prototype.reduce()"
},
"inject": {
"compatible": false,
"alternative": "Array.prototype.reduce()"
},
"foldl": {
"compatible": false,
"alternative": "Array.prototype.reduce()"
},
"reduceRight": {
"compatible": false,
"alternative": "Array.prototype.reduceRight()"
},
"foldr": {
"compatible": false,
"alternative": "Array.prototype.reduceRight()"
},
"size": {
"compatible": false,
"alternative": "Array.prototype.length"
},
"some": {
"compatible": false,
"alternative": "Array.prototype.some()"
},
"any": {
"compatible": false,
"alternative": "Array.prototype.some()"
},
"includes": {
"compatible": false,
"alternative": "Array.prototype.includes()",
"ES6": true
},
"contains": {
"compatible": false,
"alternative": "Array.prototype.includes()",
"ES6": true
},
"slice": {
"compatible": true,
"alternative": "Array.prototype.slice()"
},
"takeRight": {
"compatible": false,
"alternative": "Array.prototype.slice()"
},
"bind": {
"ruleName": "bind",
"compatible": true,
"alternative": "Function.prototype.bind()"
},
"isFinite": {
"compatible": true,
"alternative": "Number.isFinite()"
},
"isInteger": {
"ruleName": "is-integer",
"compatible": true,
"alternative": "Number.isInteger()",
"ES6": true
},
"isNaN": {
"ruleName": "is-nan",
"compatible": true,
"alternative": "Number.isNaN()",
"ES6": true
},
"isNil": {
"ruleName": "is-nil",
"compatible": true,
"alternative": "value === null || value === undefined"
},
"isNull": {
"ruleName": "is-null",
"compatible": true,
"alternative": "value === null"
},
"isUndefined": {
"ruleName": "is-undefined",
"compatible": true,
"alternative": "value === undefined"
},
"keys": {
"compatible": true,
"alternative": "Object.keys()"
},
"extendOwn": {
"compatible": true,
"alternative": "Object.assign()",
"ES6": true
},
"assign": {
"compatible": true,
"alternative": "Object.assign()",
"ES6": true
},
"values": {
"compatible": true,
"alternative": "Object.values()",
"ES6": true
},
"entries": {
"compatible": true,
"alternative": "Object.entries()",
"ES6": true
},
"toPairs": {
"compatible": true,
"alternative": "Object.entries()",
"ES6": true
},
"pairs": {
"compatible": true,
"alternative": "Object.entries()",
"ES6": true
},
"get": {
"compatible": false,
"alternative": "optional chaining to get nested values and nullish coalescing operator for fallback values",
"ES11": true
},
"split": {
"compatible": true,
"alternative": "String.prototype.split()"
},
"startsWith": {
"ruleName": "starts-with",
"compatible": true,
"alternative": "String.prototype.startsWith()"
},
"endsWith": {
"ruleName": "ends-with",
"compatible": true,
"alternative": "String.prototype.endsWith()"
},
"toLower": {
"compatible": true,
"alternative": "String.prototype.toLowerCase()"
},
"toUpper": {
"compatible": true,
"alternative": "String.prototype.toUpperCase()"
},
"trim": {
"compatible": true,
"alternative": "String.prototype.trim()"
},
"padStart": {
"compatible": true,
"alternative": "String.prototype.padStart()",
"ES6": true
},
"padEnd": {
"compatible": true,
"alternative": "String.prototype.padEnd()",
"ES6": true
},
"repeat": {
"compatible": true,
"alternative": "String.prototype.repeat()",
"ES6": true
},
"uniq": {
"compatible": true,
"alternative": "[... new Set(arr)]",
"ES6": true
},
"replace": {
"compatible": true,
"alternative": "String.prototype.replace()"
},
"omit": {
"compatible": true,
"alternative": "{a, b, c, ...notOmittedValues}",
"ES6": true
},
"flatten": {
"compatible": true,
"alternative": "Array.prototype.reduce((a,b) => a.concat(b), [])"
},
"throttle": {
"compatible": true,
"alternative": "Example of native implementation: https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore#_throttle"
},
"isString": {
"compatible": true,
"alternative": "str != null && typeof str.valueOf() === \"string\""
},
"castArray": {
"compatible": true,
"alternative": "Array.isArray(arr) ? arr : [arr]"
},
"cloneDeep": {
"compatible": true,
"alternative": "structuredClone()"
},
"isFunction": {
"compatible": true,
"alternative": "typeof func === \"function\""
},
"unionBy": {
"compatible": false,
"alternative": "Example of native implementation: https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore#_unionBy",
"ES10": true
},
"capitalize": {
"compatible": true,
"alternative": "string.charAt(0).toUpperCase() + string.slice(1).toLowerCase()"
},
"isDate": {
"compatible": true,
"alternative": "String.prototype.toString.call()"
},
"defaults": {
"compatible": true,
"alternative": "Object.assign({}, defaultValues, newValues)",
"ES6": true
},
"isArrayBuffer": {
"compatible": false,
"alternative": "value instanceof ArrayBuffer"
},
"head": {
"compatible": true,
"alternative": "Array.prototype.at(0)",
"ES13": true
}
}
================================================
FILE: package.json
================================================
{
"name": "eslint-plugin-you-dont-need-lodash-underscore",
"version": "6.14.0",
"description": "Check methods you can use natively without lodash/underscore",
"repository": {
"type": "git",
"url": "https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore.git"
},
"keywords": [
"underscore",
"lodash",
"eslint",
"eslintplugin",
"eslint-plugin",
"native"
],
"author": "Robert Chang <cht8687@gmail.com>",
"contributors": [
"Patrick McElhaney <pmcelhaney@gmail.com> (http://patrickmcelhaney.com)",
"Steve Mao <maochenyan@gmail.com> (https://github.com/stevemao)"
],
"main": "index.js",
"scripts": {
"coveralls": "cat ./coverage/lcov.info | coveralls",
"test": "istanbul cover tests",
"test:unit": "mocha tests/unit"
},
"dependencies": {
"kebab-case": "^1.0.0"
},
"devDependencies": {
"coveralls": "^3.1.1",
"eslint": "^8.48.0",
"istanbul": "^0.4.4",
"lodash": "^4.17.4",
"mocha": "^10.2.0"
},
"engines": {
"node": ">=4.0"
},
"license": "MIT",
"bugs": {
"url": "https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore/issues"
},
"homepage": "https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore.git"
}
================================================
FILE: tests/index.js
================================================
require('./lib/rules/all.js');
const assert = require('assert');
const plugin = require('../');
assert.equal(plugin.configs['all-warn'].rules['you-dont-need-lodash-underscore/contains'], 1);
assert.equal(plugin.configs['all-warn'].rules['you-dont-need-lodash-underscore/trim'], 1);
assert.equal(plugin.configs.all.rules['you-dont-need-lodash-underscore/every'], 2);
assert.equal(plugin.configs.all.rules['you-dont-need-lodash-underscore/keys'], 2);
assert.equal(plugin.configs['compatible-warn'].rules['you-dont-need-lodash-underscore/each'], undefined);
assert.equal(plugin.configs['compatible-warn'].rules['you-dont-need-lodash-underscore/last-index-of'], 1);
assert.equal(plugin.configs.compatible.rules['you-dont-need-lodash-underscore/for-each'], 1);
assert.equal(plugin.configs.compatible.rules['you-dont-need-lodash-underscore/is-nan'], 2);
================================================
FILE: tests/lib/rules/all.js
================================================
'use strict';
const RuleTester = require('eslint').RuleTester;
const assert = require('assert');
const rules = require('../../../lib/rules/all');
const allRules = require('../../../lib/rules/rules');
const ruleTester = new RuleTester({
parserOptions: { ecmaVersion: 2018, sourceType: "module" }
});
// Only a couple of smoke tests because otherwise it would get very redundant
ruleTester.run('_.concat', rules.concat, {
valid: [
'array.concat(2, [3], [[4]])'
],
invalid: [{
code: '_.concat(array, 2, [3], [[4]])',
errors: ['Consider using the native Array.prototype.concat()']
}]
});
ruleTester.run('lodash.keys', rules.keys, {
valid: [
'Object.keys({one: 1, two: 2, three: 3})'
],
invalid: [{
code: 'lodash.keys({one: 1, two: 2, three: 3})',
errors: ['Consider using the native Object.keys()']
}]
});
ruleTester.run(`Import lodash.isnan`, rules['is-nan'], {
valid: [`{ x: require('lodash') }`],
invalid: [{
code: `import isNaN from 'lodash/isNaN';`,
errors: [`Import from 'lodash/isNaN' detected. Consider using the native Number.isNaN()`]
}, {
code: `import isNaN from 'lodash.isnan';`,
errors: [`Import from 'lodash.isnan' detected. Consider using the native Number.isNaN()`]
}, {
code: `import { isNaN as x } from 'lodash';`,
errors: [`Import { isNaN } from 'lodash' detected. Consider using the native Number.isNaN()`]
}, {
code: `const { isNaN: x } = require('lodash');`,
errors: [`{ isNaN } = require('lodash') detected. Consider using the native Number.isNaN()`]
}, {
code: `({ isNaN: x } = require('lodash'));`,
errors: [`{ isNaN } = require('lodash') detected. Consider using the native Number.isNaN()`]
}, {
code: `require('lodash/isNaN');`,
errors: [`require('lodash/isNaN') detected. Consider using the native Number.isNaN()`]
}, {
code: `require('lodash.isnan');`,
errors: [`require('lodash.isnan') detected. Consider using the native Number.isNaN()`]
}]
});
ruleTester.run(`Import { isNaN } from lodash-es`, rules['is-nan'], {
valid: [`{ x: require('lodash-es') }`],
invalid: [{
code: `import { isNaN } from 'lodash-es';`,
errors: [`Import { isNaN } from 'lodash-es' detected. Consider using the native Number.isNaN()`]
},
{
code: `import isNaN from 'lodash-es/isNaN';`,
errors: [`Import from 'lodash-es/isNaN' detected. Consider using the native Number.isNaN()`]
}, {
code: `import { isNaN as x } from 'lodash-es';`,
errors: [`Import { isNaN } from 'lodash-es' detected. Consider using the native Number.isNaN()`]
}, {
code: `const { isNaN: x } = require('lodash-es');`,
errors: [`{ isNaN } = require('lodash-es') detected. Consider using the native Number.isNaN()`]
}, {
code: `({ isNaN: x } = require('lodash-es'));`,
errors: [`{ isNaN } = require('lodash-es') detected. Consider using the native Number.isNaN()`]
}, {
code: `require('lodash-es/isNaN');`,
errors: [`require('lodash-es/isNaN') detected. Consider using the native Number.isNaN()`]
}]
});
ruleTester.run('underscore.forEach', rules['for-each'], {
valid: [
'[0, 1].forEach()',
"Object.entries({'one':1,'two':2}).forEach()"
],
invalid: [{
code: 'underscore.forEach()',
errors: ['Consider using the native Array.prototype.forEach() or Object.entries().forEach()']
}]
});
ruleTester.run('underscore.isNaN', rules['is-nan'], {
valid: [
'Number.isNaN(NaN);'
],
invalid: [{
code: 'underscore.isNaN(NaN)',
errors: ['Consider using the native Number.isNaN()']
}]
});
ruleTester.run('_.first', rules['first'], {
valid: [
'[0, 1, 3][0]',
'[0, 1, 3].at(0)',
'[0, 1, 3].slice(0, 2)'
],
invalid: [{
code: '_.first([0, 1, 3])',
errors: ['Consider using the native Array.prototype.at(0) or Array.prototype.slice()']
}, {
code: '_.first([0, 1, 3], 2)',
errors: ['Consider using the native Array.prototype.at(0) or Array.prototype.slice()']
}]
});
ruleTester.run('_.last', rules['last'], {
valid: [
'var numbers = [0, 1, 3]; numbers[numbers.length - 1]',
'[0, 1, 3].at(-1)',
'[0, 1, 3].slice(-2)'
],
invalid: [{
code: '_.last([0, 1, 3])',
errors: ['Consider using the native Array.prototype.at(-1) or Array.prototype.slice()']
}, {
code: '_.last([0, 1, 3], 2)',
errors: ['Consider using the native Array.prototype.at(-1) or Array.prototype.slice()']
}]
});
ruleTester.run('_', rules.concat, {
valid: [
'_(2, [3], [[4]])'
],
invalid: []
});
ruleTester.run('_.isUndefined', rules['is-undefined'], {
valid: [
'2 === undefined'
],
invalid: [{
code: '_.isUndefined(2)',
errors: ['Consider using the native value === undefined']
},{
code: '_(2).isUndefined()',
errors: ['Consider using the native value === undefined']
}]
});
/*This is to make sure that You-Dont-Need-Lodash can handle the
evaluation of nested functions that had caused an error noted in the comments of
Pull Request #219*/
ruleTester.run('Nested functions', rules['is-undefined'], {
valid: [
`function myNestedFunction(firstInput) {
return (secondInput) => {
return firstInput + secondInput
}
}
myNestedFunction(2)(2)`
],
invalid: []
});
/*Test for new flatten rule*/
ruleTester.run('_.flatten', rules['flatten'], {
valid: [
`[1,2,[3,4]].reduce((a,b) => a.concat(b), [])`,
`[1,2,[3,4]].flat()`,
`[1,2,[3,4]].flatMap(a => a)`
],
invalid: [{
code: `_.flatten([1,2,[3,4]])`,
errors: [`Consider using the native Array.prototype.reduce((a,b) => a.concat(b), [])`]
},{
code: `_([1,2,[3,4]]).flatten()`,
errors: [`Consider using the native Array.prototype.reduce((a,b) => a.concat(b), [])`]
}]
});
ruleTester.run('_.isUndefined', rules['is-undefined'], {
valid: [
'2 === undefined'
],
invalid: [{
code: '_.isUndefined(2)',
errors: ['Consider using the native value === undefined']
},{
code: '_(2).isUndefined()',
errors: ['Consider using the native value === undefined']
}]
});
ruleTester.run('_.startsWith', rules['starts-with'], {
valid: [
'"abc".startsWith("a")',
'"abc".startsWith("b", 1)'
],
invalid: [{
code: '_.startsWith("abc", "a")',
errors: ['Consider using the native String.prototype.startsWith()']
},{
code: '_.startsWith("abc", "b", 1)',
errors: ['Consider using the native String.prototype.startsWith()']
}]
});
ruleTester.run('_.endsWith', rules['ends-with'], {
valid: [
'"abc".endsWith("c")',
'"abc".endsWith("b", 1)'
],
invalid: [{
code: '_.endsWith("abc", "c")',
errors: ['Consider using the native String.prototype.endsWith()']
},{
code: '_.endsWith("abc", "b", 1)',
errors: ['Consider using the native String.prototype.endsWith()']
}]
});
ruleTester.run('_.head', rules['head'], {
valid: [
'[0, 1, 3].at(0)',
],
invalid: [{
code: '_.head([0, 1, 3])',
errors: ['Consider using the native Array.prototype.at(0)']
}]
});
================================================
FILE: tests/unit/all.js
================================================
'use strict';
const assert = require('assert');
const _ = require('lodash');
describe('code snippet example', () => {
it('compact', () => {
assert.deepEqual(
_.compact([0, 1, false, 2, '', 3]),
[0, 1, false, 2, '', 3].filter(v => v)
)
})
it('concat', () => {
const lodashArray = [1]
const lodashResult = _.concat(lodashArray, 2, [3], [[4]])
const nativeArray = [1]
const nativeResult = nativeArray.concat(2, [3], [[4]])
assert.deepEqual(lodashResult, nativeResult)
})
it('invert', () => {
var object = { 'a': 1, 'b': '2', 'c': 3 };
function invert(object) {
var obj = {};
for (var key in object) {
if (object.hasOwnProperty(key)) {
obj[object[key]] = key;
}
}
return obj;
}
assert.deepEqual(
_.invert(object),
invert(object)
)
})
it('mapKeys', () => {
var object = { 'a': 1, 'b': 2 };
function mapKeys(object, cb) {
var obj = {};
for (var key in object) {
if (object.hasOwnProperty(key)) {
var newKey = cb(object[key], key, object);
obj[newKey] = object[key];
}
}
return obj;
}
assert.deepEqual(
_.mapKeys(object, function (value, key) {
return key + value;
}),
mapKeys(object, function (value, key) {
return key + value;
})
)
})
it('pick', () => {
var object = { 'a': 1, 'b': '2', 'c': 3 };
function pick(object, keys) {
return keys.reduce((obj, key) => {
if (object && object.hasOwnProperty(key)) {
obj[key] = object[key];
}
return obj;
}, {});
}
assert.deepEqual(
_.pick(object, ['a', 'c', 'x']),
pick(object, ['a', 'c', 'x'])
)
})
it('pickBy', () => {
var object = { 'a': 1, 'b': null, 'c': 3, 'd': false, 'e': undefined, 'f': '', 'g': 0 };
function pickBy(object) {
const obj = {};
for (const key in object) {
if (object[key]) {
obj[key] = object[key];
}
}
return obj;
}
assert.deepEqual(
_.pickBy(object),
pickBy(object)
)
})
describe('fill', () => {
it("_.fill(array, 'a')", () => {
var array = [1, 2, 3]
assert.deepEqual(
_.fill(array, 'a'),
array.fill('a')
)
})
it("_.fill(Array(3), 2)", () => {
assert.deepEqual(
_.fill(Array(3), 2),
Array(3).fill(2)
)
})
it("_.fill([4, 6, 8, 10], '*', 1, 3)", () => {
assert.deepEqual(
_.fill([4, 6, 8, 10], '*', 1, 3),
[4, 6, 8, 10].fill('*', 1, 3)
)
})
})
describe('chunk', () => {
const chunk = (input, size) => {
return input.reduce((arr, item, idx) => {
return idx % size === 0
? [...arr, [item]]
: [...arr.slice(0, -1), [...arr.slice(-1)[0], item]];
}, []);
};
it("_.chunk(['a', 'b', 'c', 'd'], 2);", () => {
assert.deepEqual(
_.chunk(['a', 'b', 'c', 'd'], 2),
chunk(['a', 'b', 'c', 'd'], 2)
)
})
it("_.chunk(['a', 'b', 'c', 'd'], 3);", () => {
assert.deepEqual(
_.chunk(['a', 'b', 'c', 'd'], 3),
chunk(['a', 'b', 'c', 'd'], 3)
)
})
})
describe('times', () => {
const times = (n, fn = (_, x) => x) => {
return Array.from(Array(n), fn)
};
it("_.times(10);", () => {
assert.deepEqual(
_.times(10),
times(10)
)
})
it("_.times(10, x => x + 1);", () => {
assert.deepEqual(
_.times(10, x => x + 1),
times(10, (_, x) => x + 1)
)
})
})
describe('assign', () => {
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
const assign = (target, ...sources) => Object.assign(target, ...sources);
it("_.assign({}, new Foo, new Bar);", () => {
assert.deepEqual(
_.assign({}, new Foo, new Bar),
assign({}, new Foo, new Bar)
)
})
it("_.assign(new Foo, new Bar);", () => {
assert.deepEqual(
_.assign(new Foo, new Bar),
assign(new Foo, new Bar)
)
})
})
describe('extend', () => {
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
const extend = (target, ...sources) => {
const length = sources.length;
if (length < 1 || target == null) return target;
for (let i = 0; i < length; i++) {
const source = sources[i];
for (const key in source) {
target[key] = source[key];
}
}
return target;
};
it("_.extend({}, new Foo, new Bar);", () => {
assert.deepEqual(
_.extend({}, new Foo, new Bar),
extend({}, new Foo, new Bar)
)
})
it("_.extend(new Foo, new Bar);", () => {
assert.deepEqual(
_.extend(new Foo, new Bar),
extend(new Foo, new Bar)
)
})
})
describe('isDate', () => {
const isDate = (obj) => {
return (obj ? Object.prototype.toString.call(obj) === "[object Date]" : false);
};
it ('_.Date(null)', () => {
assert.equal(
_.isDate(null),
isDate(null)
)
})
it ("_.Date('Mon April 23 2012')", () => {
assert.equal(
_.isDate('Mon April 23 2012'),
isDate('Mon April 23 2012')
)
})
it ('_.Date(new Date)', () => {
assert.equal(
_.isDate(new Date),
isDate(new Date)
)
})
})
describe('isEmpty', () => {
const isEmpty = (obj) => {
return (obj ? [Object, Array].includes(obj.constructor) && !Object.entries(obj).length : true);
};
it ('_.isEmpty(null)', () => {
assert.equal(
_.isEmpty(null),
isEmpty(null)
)
})
it ("_.isEmpty('')", () => {
assert.equal(
_.isEmpty(''),
isEmpty('')
)
})
it ("_.isEmpty({})", () => {
assert.equal(
_.isEmpty({}),
isEmpty({})
)
})
it ("_.isEmpty([])", () => {
assert.equal(
_.isEmpty([]),
isEmpty([])
)
})
it ("_.isEmpty({a: '1'})", () => {
assert.equal(
_.isEmpty({a: '1'}),
isEmpty({a: '1'})
)
})
})
describe('isInteger', () => {
it('_.isInteger(3)', () => {
assert.equal(
_.isInteger(3),
Number.isInteger(3)
)
})
it('_.isInteger("3")', () => {
assert.equal(
_.isInteger("3"),
Number.isInteger("3")
)
})
it('_.isInteger(2.9)', () => {
assert.equal(
_.isInteger(2.9),
Number.isInteger(2.9)
)
})
it('_.isInteger(NaN)', () => {
assert.equal(
_.isInteger(NaN),
Number.isInteger(NaN)
)
})
})
describe('isPlainObject', () => {
function isPlainObject(value) {
if (typeof value !== 'object' || value === null) return false
if (Object.prototype.toString.call(value) !== '[object Object]') return false
const proto = Object.getPrototypeOf(value);
if (proto === null) return true
const Ctor = Object.prototype.hasOwnProperty.call(proto, 'constructor') && proto.constructor;
return (
typeof Ctor === 'function' &&
Ctor instanceof Ctor && Function.prototype.call(Ctor) === Function.prototype.call(value)
);
}
function Foo() {
this.a = 1;
}
it('_.isPlainObject(NaN)', () => {
assert.equal(
_.isPlainObject(NaN),
isPlainObject(NaN)
)
})
it('_.isPlainObject([1, 2, 3])', () => {
assert.equal(
_.isPlainObject([1, 2, 3]),
isPlainObject([1, 2, 3])
)
})
it('_.isPlainObject(null)', () => {
assert.equal(
_.isPlainObject(null),
isPlainObject(null)
)
})
it("_.isPlainObject({ 'x': 0, 'y': 0 })", () => {
assert.equal(
_.isPlainObject({ 'x': 0, 'y': 0 }),
isPlainObject({ 'x': 0, 'y': 0 })
)
})
it("_.isPlainObject(Object.create(null))", () => {
assert.equal(
_.isPlainObject(Object.create(null)),
isPlainObject(Object.create(null))
)
})
it("_.isPlainObject(Object.create(new Foo()))", () => {
assert.equal(
_.isPlainObject(Object.create(new Foo())),
isPlainObject(Object.create(new Foo()))
)
})
it("_.isPlainObject(Object.create(new Date()))", () => {
assert.equal(
_.isPlainObject(Object.create(new Date())),
isPlainObject(Object.create(new Date()))
)
})
})
describe('get', () => {
const get = (obj, path, defaultValue) => {
const travel = regexp =>
String.prototype.split
.call(path, regexp)
.filter(Boolean)
.reduce((res, key) => (res !== null && res !== undefined ? res[key] : res), obj);
const result = travel(/[,[\]]+?/) || travel(/[,[\].]+?/);
return result === undefined || result === obj ? defaultValue : result;
};
var obj = {
aa: [{ b: { c: 0 }, 1: 0 }],
dd: { ee: { ff: 2 } },
gg: { h: 2 },
"gg.h": 1,
"kk.ll": { "mm.n": [3, 4, { "oo.p": 5 }] }
};
it ("should handle falsy values", () => {
var val = _.get(obj, 'aa[0].b.c', 1)
assert.strictEqual(val, get(obj, 'aa[0].b.c', 1))
assert.notEqual(val, 1)
})
it ("should handle just bracket notation", () => {
var val = _.get(obj, 'aa[0][1]', 1)
assert.strictEqual(val, get(obj, 'aa[0][1]', 1))
assert.notEqual(val, 1)
})
it ("should handle just period notation", () => {
var val = _.get(obj, 'dd.ee.ff', 1)
assert.strictEqual(val, get(obj, 'dd.ee.ff', 1))
assert.notEqual(val, 1)
})
it ("should handle neither notation", () => {
var val = _.get(obj, 'aa', 1)
assert.deepEqual(val, get(obj, 'aa', 1))
assert.notEqual(val, 1)
})
it ("should handle both notation", () => {
var val = _.get(obj, 'aa[0].b.c', 1)
assert.strictEqual(val, get(obj, 'aa[0].b.c', 1))
assert.notEqual(val, 1)
})
it ("should handle array path", () => {
var val = _.get(obj, ['aa', [0], 'b', 'c'], 1)
assert.strictEqual(val, get(obj, ['aa', [0], 'b', 'c'], 1))
assert.notEqual(val, 1)
})
it ("should handle undefined without default", () => {
var val = _.get(obj, 'dd.b')
assert.strictEqual(val, get(obj, 'dd.b'))
})
it ("should handle undefined with default", () => {
var val = _.get(obj, 'dd.b', 1)
assert.strictEqual(val, get(obj, 'dd.b', 1))
})
it ("should handle deep undefined without default", () => {
var val = _.get(obj, 'dd.b.c')
assert.strictEqual(val, get(obj, 'dd.b.c'))
})
it ("should handle deep undefined with default", () => {
var val = _.get(obj, 'dd.b.c', 1)
assert.strictEqual(val, get(obj, 'dd.b.c', 1))
assert.strictEqual(val, 1);
})
it ("should handle null default", () => {
var val = _.get(obj, 'dd.b', null)
assert.strictEqual(val, get(obj, 'dd.b', null))
assert.strictEqual(val, null);
})
it ("should handle empty path", () => {
var val = _.get(obj, '', 1)
assert.strictEqual(val, get(obj, '', 1))
assert.notEqual(val, obj);
})
it ("should handle undefined obj", () => {
var val = _.get(undefined, 'aa')
assert.strictEqual(val, get(undefined, 'aa'))
})
it ("should handle path contains a key with dots", () => {
var val = _.get(obj, 'gg.h')
assert.strictEqual(val, get(obj, 'gg.h'))
assert.strictEqual(val, 1)
})
it ("should handle array path of keys with dots", () => {
var val = _.get(obj, ["kk.ll", "mm.n", 0, "oo.p"])
assert.strictEqual(
val,
get(obj, ["kk.ll", "mm.n", 0, "oo.p"])
);
})
})
describe('split', () => {
const source = 'a-b-c';
const separator = '-';
const limit = 2;
it(`_.split("${source}", "${separator}")`, () => {
assert.deepEqual(
_.split(source, separator),
source.split(separator)
);
})
it(`_.split("${source}", "${separator}", ${limit})`, () => {
assert.deepEqual(
_.split(source, separator, limit),
source.split(separator, limit)
);
})
})
describe('inRange', () => {
const inRange = (num, init, final) => {
if(final === undefined){
final = init;
init = 0;
}
return (num >= Math.min(init, final) && num < Math.max(init, final));
}
it('_.inRange(3, 2, 4)', () => {
assert.equal(
_.inRange(3, 2, 4),
inRange(3, 2, 4)
)
});
it('_.inRange(4, 8)', () => {
assert.equal(
_.inRange(4, 8),
inRange(4, 8)
)
});
it('_.inRange(4, 2)', () => {
assert.equal(
_.inRange(4, 2),
inRange(4, 2)
)
});
it('_.inRange(2, 2)', () => {
assert.equal(
_.inRange(2, 2),
inRange(2, 2)
)
});
it('_.inRange(1.2, 2)', () => {
assert.equal(
_.inRange(1.2, 2),
inRange(1.2, 2)
)
});
it('_.inRange(5.2, 4)', () => {
assert.equal(
_.inRange(5.2, 4),
inRange(5.2, 4)
)
});
it('_.inRange(-3, -2, -6)', () => {
assert.equal(
_.inRange(-3, -2, -6),
inRange(-3, -2, -6)
)
});
it('_.inRange(1, 1, 5)', () => {
assert.equal(
_.inRange(1, 1, 5),
inRange(1, 1, 5)
)
});
})
describe('random', () => {
const random = (a = 1, b = 0) => {
const lower = Math.min(a, b);
const upper = Math.max(a, b);
return lower + Math.random() * (upper - lower);
};
const array = Array(1000).fill(0);
it('random() in range [0, 1]', () => {
assert.ok(array.every(() => {
const randomValue = random();
return randomValue >= 0 && randomValue <= 1;
}));
});
it('random() is float', () => {
assert.ok(array.some(() => {
const randomValue = random();
return !Number.isInteger(randomValue);
}));
});
it('random(5) in range [0, 5]', () => {
assert.ok(array.every(() => {
const randomValue = random(5);
return randomValue >= 0 && randomValue <= 5;
}));
});
it('random(5) is float', () => {
assert.ok(array.some(() => {
const randomValue = random(5);
return !Number.isInteger(randomValue);
}));
});
it('random(-10) supports negative', () => {
assert.ok(array.every(() => {
const randomValue = random(-10);
return randomValue <= 0;
}));
});
it('random(10, 5) swap the bounds', () => {
assert.ok(array.every(() => {
const randomValue = random(10, 5);
return randomValue >= 5 && randomValue <= 10;
}));
});
it('random(-10, 10) supports negative', () => {
assert.ok(array.some(() => {
const randomValue = random(-10, 10);
return randomValue > 0;
}));
assert.ok(array.some(() => {
const randomValue = random(-10, 10);
return randomValue < 0;
}));
});
it('random(-10, 10) in range [-10, 10]', () => {
assert.ok(array.every(() => {
const randomValue = random(-10, 10);
return randomValue >= -10 && randomValue <= 10;
}));
});
it('random(1.2, 5.2) supports floats', () => {
assert.ok(array.every(() => {
const randomValue = random(1.2, 5.2);
return randomValue >= 1.2 && randomValue <= 5.2;
}));
});
it('random(100000, 100001) in range [100000, 100001]', () => {
assert.ok(array.every(() => {
const randomValue = random(100000, 100001);
return randomValue >= 100000 && randomValue <= 100001;
}));
});
});
describe('randomInt', () => {
const randomInt = (a = 1, b = 0) => {
const lower = Math.ceil(Math.min(a, b));
const upper = Math.floor(Math.max(a, b));
return Math.floor(lower + Math.random() * (upper - lower + 1))
};
const array = Array(1000).fill(0);
const uniq = (arr) => [...new Set(arr)];
it('randomInt() return `0` or `1`', () => {
const randoms = uniq(array.map(() => {
return randomInt();
})).sort();
assert.deepStrictEqual(randoms, [0, 1]);
});
it('randomInt(5) in range [0, 5]', () => {
assert.ok(array.every(() => {
const randomValue = randomInt(5);
return randomValue >= 0 && randomValue <= 5;
}));
});
it('randomInt(5) is integer', () => {
assert.ok(array.some(() => {
const randomValue = randomInt(5);
return Number.isInteger(randomValue);
}));
});
it('randomInt(-10) supports negative', () => {
assert.ok(array.every(() => {
const randomValue = randomInt(-10);
return randomValue <= 0;
}));
});
it('randomInt(10, 5) swap the bounds', () => {
assert.ok(array.every(() => {
const randomValue = randomInt(10, 5);
return randomValue >= 5 && randomValue <= 10;
}));
});
it('randomInt(-10, 10) supports negative', () => {
assert.ok(array.some(() => {
const randomValue = randomInt(-10, 10);
return randomValue > 0;
}));
assert.ok(array.some(() => {
const randomValue = randomInt(-10, 10);
return randomValue < 0;
}));
});
it('randomInt(-10, 10) in range [-10, 10]', () => {
assert.ok(array.every(() => {
const randomValue = randomInt(-10, 10);
return randomValue >= -10 && randomValue <= 10;
}));
});
it('randomInt(1.2, 5.2) supports floats', () => {
assert.ok(array.every(() => {
const randomValue = randomInt(1.2, 5.2);
return randomValue >= 2 && randomValue <= 5;
}));
});
it('randomInt(100000, 100001) return `100000` or `100001`', () => {
const randoms = uniq(array.map(() => {
return randomInt(100000, 100001);
})).sort();
assert.deepStrictEqual(randoms, [100000, 100001]);
});
});
describe('clamp', () => {
const clamp = (number, boundOne, boundTwo) => {
if (!boundTwo) {
return Math.max(number, boundOne) === boundOne ? number : boundOne;
} else if (Math.min(number, boundOne) === number) {
return boundOne;
} else if (Math.max(number, boundTwo) === number) {
return boundTwo;
}
return number;
};
it('clamp(-10, -5, 5) returns lower bound if number is less than it', () => {
assert.deepStrictEqual(clamp(-10, -5, 5), -5);
});
it('clamp(10, -5, 5) returns upper bound if number is greater than it', () => {
assert.deepStrictEqual(clamp(10, -5, 5), 5);
});
it('clamp(10, -5) treats second parameter as upper bound', () => {
assert.deepStrictEqual(clamp(10, -5), -5);
});
});
describe('padStart', () => {
it('_.padStart("123", 5, "0")', () => {
assert.equal(
_.padStart("123", 5, '0'),
"123".padStart(5, '0')
);
})
it('_.padStart("123", 6, "_-")', () => {
assert.equal(
_.padStart("123", 6, '_-'),
"123".padStart(6, '_-')
);
})
})
describe('padEnd', () => {
it('_.padEnd("123", 5, "0")', () => {
assert.equal(
_.padEnd("123", 5, '0'),
"123".padEnd(5, '0')
);
})
it('_.padEnd("123", 6, "_-")', () => {
assert.equal(
_.padEnd("123", 6, '_-'),
"123".padEnd(6, '_-')
);
})
})
describe('upperFirst', () => {
const upperFirst = (string) => {
return string ? string.charAt(0).toUpperCase() + string.slice(1) : ''
}
it('_.upperFirst("george")', () => {
assert.equal(
_.upperFirst('george'),
upperFirst('george')
)
})
it('_.upperFirst(null)', () => {
assert.equal(
_.upperFirst(null),
upperFirst(null)
)
})
it('_.upperFirst("")', () => {
assert.equal(
_.upperFirst(''),
upperFirst('')
)
})
})
describe('isString', () => {
function isString(str) {
if (str != null && typeof str.valueOf() === "string") {
return true
}
return false
}
it('_.isString("abc")', () => {
assert.deepEqual(_.isString("abc"),
isString("abc"))
});
it('_.isString(1)', () => {
assert.deepEqual(_.isString(1),
isString(1))
});
it('_.isString("")', () => {
assert.deepEqual(_.isString(''),
isString(''))
})
});
describe('lowerFirst', () => {
const lowerFirst = (string) => {
return string ? string.charAt(0).toLowerCase() + string.slice(1) : ''
}
it('_.lowerFirst("Fred")', () => {
assert.equal(
_.lowerFirst('fred'),
lowerFirst('fred')
)
})
it('_.lowerFirst(null)', () => {
assert.equal(
_.lowerFirst(null),
lowerFirst(null)
)
})
it('_.lowerFirst("")', () => {
assert.equal(
_.lowerFirst(''),
lowerFirst('')
)
})
})
describe('isUndefined', () => {
const definedVariable = 1; //defined variable (will return false)
let undefinedVariable; //undefined variable (will return true)
it('_.isUndefined(definedVariable)', () => {
assert.equal(_.isUndefined(definedVariable),
(definedVariable === undefined))
});
it('_(definedVariable).isUndefined()', () => {
assert.equal(_(definedVariable).isUndefined(),
(definedVariable === undefined))
});
it('_.isUndefined(undefinedVariable)', () => {
assert.equal(_.isUndefined(undefinedVariable),
(undefinedVariable === undefined))
});
it('_(undefinedVariable).isUndefined()', () => {
assert.equal(_(undefinedVariable).isUndefined(),
(undefinedVariable === undefined))
});
});
describe('flatten', () => {
it('_.flatten(twoLayerArray)', () => {
const testArray = [1,2[3,4]];
assert.deepEqual(_.flatten(testArray),
testArray.reduce((a,b) => a.concat(b), []))
});
it('_.flatten(multiLayerArray)', () => {
const testArray = [1,2[3,4,[5,6,[7,8]]]];
assert.deepEqual(_.flatten(testArray),
testArray.reduce((a,b) => a.concat(b), []))
});
});
describe('forEach', () => {
it('_.forEach(array)', () => {
const testArray = [1,2,3,4];
let lodashOutput = []
let nativeOutput = []
_.forEach(testArray, element => {
lodashOutput.push(element);
});
testArray.forEach(element => {
nativeOutput.push(element);
});
assert.deepEqual(lodashOutput,nativeOutput);
});
it('_.forEach(object)', () => {
const testObject = {
'one':1,
'two':2,
'three':3,
'four':4,
}
let lodashOutput = []
let nativeOutput = []
_.forEach(testObject, value => {
lodashOutput.push(value);
});
Object.entries(testObject).forEach(([key,value]) => {
nativeOutput.push(value);
});
assert.deepEqual(lodashOutput,nativeOutput);
});
});
describe('startsWith', () => {
it(`_.startsWith('abc', 'a')`, () => {
assert.deepEqual(
_.startsWith('abc', 'a'),
'abc'.startsWith('a')
);
});
it(`_.startsWith('abc', 'b')`, () => {
assert.deepEqual(
_.startsWith('abc', 'b'),
'abc'.startsWith('b')
);
});
it(`_.startsWith('abc', 'b', 1)`, () => {
assert.deepEqual(
_.startsWith('abc', 'b', 1),
'abc'.startsWith('b', 1)
);
});
});
describe('endsWith', () => {
it(`_.endsWith('abc', 'c')`, () => {
assert.deepEqual(
_.endsWith('abc', 'c'),
'abc'.endsWith('c')
);
});
it(`_.endsWith('abc', 'b')`, () => {
assert.deepEqual(
_.endsWith('abc', 'b'),
'abc'.endsWith('b')
);
});
it(`_.endsWith('abc', 'b', 2)`, () => {
assert.deepEqual(
_.endsWith('abc', 'b', 2),
'abc'.endsWith('b', 2)
);
});
});
describe('throttle', () => {
function throttle(func, timeFrame) {
var lastTime = 0;
return function () {
var now = new Date();
if (now - lastTime >= timeFrame) {
func();
lastTime = now;
}
};
}
it('throttle is not called more than once within timeframe', () => {
let callCount = 0;
const fn = throttle(() => callCount++, 100);
fn();
fn();
fn();
assert.equal(callCount, 1);
});
})
describe('isFunction', () => {
function isFunction(func) {
return (func && typeof func === "function")
}
it('_.isFunction(setTimeout)', () => {
assert.deepEqual(_.isFunction(setTimeout),
isFunction(setTimeout))
});
it('_.isFunction(1)', () => {
assert.deepEqual(_.isFunction(1),
isFunction(1))
});
it('_.isFunction(abc)', () => {
assert.deepEqual(_.isFunction("abc"),
isFunction("abc"))
});
});
describe('unionBy', () => {
function unionBy(...arrays) {
const iteratee = (arrays).pop();
if (Array.isArray(iteratee)) {
return []; // return empty if iteratee is missing
}
return [...arrays].flat().filter(
(set => (o) => set.has(iteratee(o)) ? false : set.add(iteratee(o)))(new Set()),
);
};
it('should take an iteratee function', () => {
assert.deepStrictEqual(_.unionBy([2.1], [1.2, 2.3], Math.floor), unionBy([2.1], [1.2, 2.3], Math.floor));
});
it('should output values from the first possible array', () => {
assert.deepStrictEqual(_.unionBy([{ x: 1, y: 1 }], [{ x: 1, y: 2 }], (x) => x.x),
unionBy([{ x: 1, y: 1 }], [{ x: 1, y: 2 }], (x) => x.x));
});
});
describe('capitalize', () => {
function capitalize(string) {
return string ? string.charAt(0).toUpperCase() + string.slice(1).toLowerCase() : '';
}
it('_.capitalize("FRED")', () => {
assert.deepStrictEqual(_.capitalize("FRED"), capitalize("FRED"));
});
it('_.capitalize("fred")', () => {
assert.deepStrictEqual(_.capitalize("fred"), capitalize("fred"));
});
it('_.capitalize("HELLO WORLD")', () => {
assert.deepStrictEqual(_.capitalize("HELLO WORLD"), capitalize("HELLO WORLD"));
});
it('_.capitalize("hello world")', () => {
assert.deepStrictEqual(_.capitalize("hello world"), capitalize("hello world"));
});
});
describe('defaults', () => {
it('sets up default values the same way', () => {
const defaultValues = { a: 1, b: 2, c: 3 };
const givenValues = { b: 4 };
const lodashObject = _.defaults(givenValues, defaultValues);
const vanillaObject = Object.assign({}, defaultValues, givenValues);
assert.deepStrictEqual(vanillaObject, { a: 1, b: 4, c: 3});
assert.deepStrictEqual(vanillaObject, lodashObject);
});
it('should handle nested values equally', () => {
const defaultValues = { a: 1, b: 2, c: { x: 3, y: 4 } };
const givenValues = { c: { x: 5 } };
const lodashObject = _.defaults(givenValues, defaultValues);
const vanillaObject = Object.assign({}, defaultValues, givenValues);
assert.deepStrictEqual(vanillaObject, { a: 1, b: 2, c: { x: 5 } })
assert.deepStrictEqual(vanillaObject, lodashObject);
});
});
describe('last', () => {
it('_.last([1,2,3,4,5])', () => {
assert.deepEqual(_.last([1,2,3,4,5]), [1,2,3,4,5].at(-1));
});
it('_.last([])', () => {
assert.deepEqual(_.last([]), [].at(-1));
});
});
describe('first', () => {
it('_.first([1,2,3,4,5])', () => {
assert.deepEqual(_.first([1,2,3,4,5]), [1,2,3,4,5].at(0));
});
it('_.first([])', () => {
assert.deepEqual(_.first([]), [].at(0));
});
})
describe('head', () => {
it('_.head([1,2,3,4,5])', () => {
assert.deepEqual(_.head([1,2,3,4,5]), [1,2,3,4,5].at(0));
});
it('_.head([])', () => {
assert.deepEqual(_.head([]), [].at(0));
});
})
});
gitextract_st3cxapu/
├── .github/
│ └── workflows/
│ ├── master.yml
│ └── pr.yml
├── .gitignore
├── .travis.yml
├── LICENSE
├── README.md
├── TEMPLATE.md
├── configuring.md
├── docs/
│ ├── .nojekyll
│ ├── README.md
│ └── index.html
├── index.js
├── lib/
│ └── rules/
│ ├── all.js
│ └── rules.json
├── package.json
└── tests/
├── index.js
├── lib/
│ └── rules/
│ └── all.js
└── unit/
└── all.js
SYMBOL INDEX (19 symbols across 3 files)
FILE: index.js
constant WARN (line 11) | const WARN = 1;
constant ERROR (line 12) | const ERROR = 2;
FILE: lib/rules/all.js
function getAssignmentLeftHandSide (line 7) | function getAssignmentLeftHandSide(node) {
method create (line 32) | create(context) {
FILE: tests/unit/all.js
function invert (line 26) | function invert(object) {
function mapKeys (line 43) | function mapKeys(object, cb) {
function pick (line 65) | function pick(object, keys) {
function pickBy (line 81) | function pickBy(object) {
function Foo (line 158) | function Foo() {
function Bar (line 161) | function Bar() {
function Foo (line 181) | function Foo() {
function Bar (line 184) | function Bar() {
function isPlainObject (line 302) | function isPlainObject(value) {
function Foo (line 317) | function Foo() {
function isString (line 786) | function isString(str) {
function throttle (line 963) | function throttle(func, timeFrame) {
function isFunction (line 987) | function isFunction(func) {
function unionBy (line 1009) | function unionBy(...arrays) {
function capitalize (line 1032) | function capitalize(string) {
Condensed preview — 18 files, each showing path, character count, and a content snippet. Download the .json file or copy for the full structured content (166K chars).
[
{
"path": ".github/workflows/master.yml",
"chars": 598,
"preview": "name: Master\n\non:\n push:\n branches: [ \"master\" ]\n\n # Allows you to run this workflow manually from the Actions tab\n"
},
{
"path": ".github/workflows/pr.yml",
"chars": 1617,
"preview": "name: PR\n\non:\n pull_request:\n types:\n - opened\n - edited\n - synchronize\n\n # Allows you to run this w"
},
{
"path": ".gitignore",
"chars": 54,
"preview": "node_modules\ncoverage\nnpm-debug.log\n/.vscode\nyarn.lock"
},
{
"path": ".travis.yml",
"chars": 139,
"preview": "language: node_js\r\n\r\nnode_js:\r\n - 10\r\n - 12\r\n - 14\r\n\r\nscript:\r\n - yarn test\r\n - yarn test:unit\r\n\r\nafter_success:\r\n "
},
{
"path": "LICENSE",
"chars": 1070,
"preview": "MIT License\n\nCopyright (c) 2018 You-Dont-Need\n\nPermission is hereby granted, free of charge, to any person obtaining a c"
},
{
"path": "README.md",
"chars": 98995,
"preview": "# [You don't (may not) need Lodash/Underscore](https://you-dont-need.github.io/You-Dont-Need-Lodash-Underscore/#/)\n\n[**\n\n1. [_.sortYourMethodAlphabetically](#_sortYourMethodAlphabetically) \n\n\n\n\n\n\n\n\n\n#"
},
{
"path": "configuring.md",
"chars": 1585,
"preview": "## Configuring the ESLint Plugin\n\n\n### If you haven't already, add ESLint to your project\n\n```sh\nnpm install --save-dev "
},
{
"path": "docs/.nojekyll",
"chars": 0,
"preview": ""
},
{
"path": "docs/README.md",
"chars": 117,
"preview": "[remoteMarkdownUrl](https://raw.githubusercontent.com/you-dont-need/You-Dont-Need-Lodash-Underscore/master/README.md)"
},
{
"path": "docs/index.html",
"chars": 1351,
"preview": "<!DOCTYPE html>\r\n<html lang=\"en\">\r\n<head>\r\n <meta charset=\"UTF-8\">\r\n <title>You don’t (may not) need Lodash/Underscore"
},
{
"path": "index.js",
"chars": 1153,
"preview": "'use strict';\nconst kebabCase = require('kebab-case');\nconst rules = require('./lib/rules/rules.json')\n\nmodule.exports.r"
},
{
"path": "lib/rules/all.js",
"chars": 3729,
"preview": "'use strict';\nconst kebabCase = require('kebab-case');\nconst rules = require('./rules');\n\nconst forbiddenLibs = ['lodash"
},
{
"path": "lib/rules/rules.json",
"chars": 8615,
"preview": "{\n \"concat\": {\n \"compatible\": true,\n \"alternative\": \"Array.prototype.concat()\"\n },\n \"drop\": {\n "
},
{
"path": "package.json",
"chars": 1256,
"preview": "{\n \"name\": \"eslint-plugin-you-dont-need-lodash-underscore\",\n \"version\": \"6.14.0\",\n \"description\": \"Check methods you "
},
{
"path": "tests/index.js",
"chars": 850,
"preview": "require('./lib/rules/all.js');\n\nconst assert = require('assert');\nconst plugin = require('../');\n\nassert.equal(plugin.co"
},
{
"path": "tests/lib/rules/all.js",
"chars": 7031,
"preview": "'use strict';\nconst RuleTester = require('eslint').RuleTester;\nconst assert = require('assert');\nconst rules = require('"
},
{
"path": "tests/unit/all.js",
"chars": 28358,
"preview": "'use strict';\nconst assert = require('assert');\nconst _ = require('lodash');\n\ndescribe('code snippet example', () => {\n\n"
}
]
About this extraction
This page contains the full source code of the you-dont-need/You-Dont-Need-Lodash-Underscore GitHub repository, extracted and formatted as plain text for AI agents and large language models (LLMs). The extraction includes 18 files (154.5 KB), approximately 51.4k tokens, and a symbol index with 19 extracted functions, classes, methods, constants, and types. Use this with OpenClaw, Claude, ChatGPT, Cursor, Windsurf, or any other AI tool that accepts text input. You can copy the full output to your clipboard or download it as a .txt file.
Extracted by GitExtract — free GitHub repo to text converter for AI. Built by Nikandr Surkov.