Repository: soyguijarro/react-storage-hooks
Branch: master
Commit: bd0a73e7c08e
Files: 23
Total size: 45.9 KB

Directory structure:
gitextract_0_crk56n/

├── .gitignore
├── .npmrc
├── .travis.yml
├── LICENSE
├── README.md
├── examples/
│   ├── .storybook/
│   │   └── main.js
│   ├── package.json
│   ├── src/
│   │   ├── Examples.stories.tsx
│   │   └── react-app-env.d.ts
│   └── tsconfig.json
├── package.json
├── src/
│   ├── common.ts
│   ├── index.ts
│   ├── reducer.ts
│   ├── state.ts
│   └── tests/
│       ├── reducer.node.test.ts
│       ├── reducer.test-d.ts
│       ├── reducer.test.ts
│       ├── state.node.test.ts
│       ├── state.test-d.ts
│       ├── state.test.ts
│       └── utils.ts
└── tsconfig.json

================================================
FILE CONTENTS
================================================

================================================
FILE: .gitignore
================================================
# Logs
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*.log
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.nuxt
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# public

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.vscode-test


================================================
FILE: .npmrc
================================================
message="Version %s"

================================================
FILE: .travis.yml
================================================
language: node_js
node_js: lts/*
cache: npm
before_script: npm install codecov -g
script: npm run check
after_success: codecov
deploy:
  provider: npm
  email: $NPM_EMAIL
  api_key: $NPM_TOKEN
  skip_cleanup: true
  on:
    tags: true
    branch: master


================================================
FILE: LICENSE
================================================
MIT License

Copyright (c) Ramón Guijarro

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
================================================
# react-storage-hooks

[![Version](https://img.shields.io/npm/v/react-storage-hooks.svg)](https://www.npmjs.com/package/react-storage-hooks)
![Dependencies](https://img.shields.io/david/soyguijarro/react-storage-hooks.svg)
![Dev dependencies](https://img.shields.io/david/dev/soyguijarro/react-storage-hooks.svg)
[![Build status](https://travis-ci.com/soyguijarro/react-storage-hooks.svg?branch=master)](https://travis-ci.com/soyguijarro/react-storage-hooks)
[![Test coverage](https://codecov.io/gh/soyguijarro/react-storage-hooks/branch/master/graph/badge.svg)](https://codecov.io/gh/soyguijarro/react-storage-hooks)
![Bundle size](https://img.shields.io/bundlephobia/minzip/react-storage-hooks.svg)
[![MIT licensed](https://img.shields.io/github/license/soyguijarro/react-storage-hooks.svg)](https://github.com/soyguijarro/react-storage-hooks/blob/master/LICENSE)

Custom [React hooks](https://reactjs.org/docs/hooks-intro) for keeping application state in sync with `localStorage` or `sessionStorage`.

:book: **Familiar API**. You already know how to use this library! Replace [`useState`](https://reactjs.org/docs/hooks-reference.html#usestate) and [`useReducer`](https://reactjs.org/docs/hooks-reference.html#usereducer) hooks with the ones in this library and get persistent state for free.

:sparkles: **Fully featured**. Automatically stringifies and parses values coming and going to storage, keeps state in sync between tabs by listening to [storage events](https://developer.mozilla.org/docs/Web/API/StorageEvent) and handles non-straightforward use cases correctly.

:zap: **Tiny and fast**. Less than 700 bytes gzipped, enforced with [`size-limit`](https://github.com/ai/size-limit). No external dependencies. Only reads from storage when necessary and writes to storage after rendering.

:capital_abcd: **Completely typed**. Written in TypeScript. Type definitions included and verified with [`tsd`](https://github.com/SamVerschueren/tsd).

:muscle: **Backed by tests**. Full coverage of the API.

## Requirements

You need to use [version 16.8.0](https://github.com/facebook/react/blob/master/CHANGELOG.md#1680-february-6-2019) or greater of React, since that's the first one to include hooks. If you still need to create your application, [Create React App](https://create-react-app.dev/) is the officially supported way.

## Installation

Add the package to your React project:

    npm install --save react-storage-hooks

Or with yarn:

    yarn add react-storage-hooks

## Usage

The `useStorageState` and `useStorageReducer` hooks included in this library work like [`useState`](https://reactjs.org/docs/hooks-reference.html#usestate) and [`useReducer`](https://reactjs.org/docs/hooks-reference.html#usereducer). The only but important differences are:

- Two additional mandatory parameters: [**`Storage` object**](https://developer.mozilla.org/en-US/docs/Web/API/Storage) (`localStorage` or `sessionStorage`) and **storage key**.
- Initial state parameters only apply if there's no data in storage for the provided key. Otherwise data from storage will be used as initial state. Think about it as **default** or **fallback state**.
- The array returned by hooks has an extra last item for **write errors**. It is initially `undefined`, and will be updated with [`Error` objects](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error) thrown by `Storage.setItem`. However the hook will keep updating state even if new values fail to be written to storage, to ensure that your application doesn't break.

### `useStorageState`

#### Example

```javascript
import React from 'react';
import { useStorageState } from 'react-storage-hooks';

function StateCounter() {
  const [count, setCount, writeError] = useStorageState(
    localStorage,
    'state-counter',
    0
  );

  return (
    <>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>+</button>
      <button onClick={() => setCount(count - 1)}>-</button>
      {writeError && (
        <pre>Cannot write to localStorage: {writeError.message}</pre>
      )}
    </>
  );
}
```

#### Signature

```typescript
function useStorageState<S>(
  storage: Storage,
  key: string,
  defaultState?: S | (() => S)
): [S, React.Dispatch<React.SetStateAction<S>>, Error | undefined];
```

### `useStorageReducer`

#### Example

```javascript
import React from 'react';
import { useStorageReducer } from 'react-storage-hooks';

function reducer(state, action) {
  switch (action.type) {
    case 'inc':
      return { count: state.count + 1 };
    case 'dec':
      return { count: state.count - 1 };
    default:
      return state;
  }
}

function ReducerCounter() {
  const [state, dispatch, writeError] = useStorageReducer(
    localStorage,
    'reducer-counter',
    reducer,
    { count: 0 }
  );

  return (
    <>
      <p>You clicked {state.count} times</p>
      <button onClick={() => dispatch({ type: 'inc' })}>+</button>
      <button onClick={() => dispatch({ type: 'dec' })}>-</button>
      {writeError && (
        <pre>Cannot write to localStorage: {writeError.message}</pre>
      )}
    </>
  );
}
```

#### Signature

```typescript
function useStorageReducer<S, A>(
  storage: Storage,
  key: string,
  reducer: React.Reducer<S, A>,
  defaultState: S
): [S, React.Dispatch<A>, Error | undefined];

function useStorageReducer<S, A, I>(
  storage: Storage,
  key: string,
  reducer: React.Reducer<S, A>,
  defaultInitialArg: I,
  defaultInit: (defaultInitialArg: I) => S
): [S, React.Dispatch<A>, Error | undefined];
```

## Advanced usage

### Alternative storage objects

The `storage` parameter of the hooks can be any object that implements the `getItem`, `setItem` and `removeItem` methods of the [`Storage` interface](https://developer.mozilla.org/en-US/docs/Web/API/Storage). Keep in mind that storage values will be automatically [serialized](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify) and [parsed](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse) before and after calling these methods.

```typescript
interface Storage {
  getItem(key: string): string | null;
  setItem(key: string, value: string): void;
  removeItem(key: string): void;
}
```

### Server-side rendering (SSR)

This library checks for the existence of the `window` object and even has some [tests in a node-like environment](https://jestjs.io/docs/en/configuration#testenvironment-string). However in your server code you will need to provide a storage object to the hooks that works server-side. A simple solution is to use a dummy object like this:

```javascript
const dummyStorage = {
  getItem: () => null,
  setItem: () => {},
  removeItem: () => {},
};
```

The important bit here is to have the `getItem` method return `null`, so that the default state parameters of the hooks get applied as initial state.

### Convenience custom hook

If you're using a few hooks in your application with the same type of storage, it might bother you to have to specify the storage object all the time. To alleviate this, you can write a custom hook like this:

```javascript
import { useStorageState } from 'react-storage-hooks';

export function useLocalStorageState(...args) {
  return useStorageState(localStorage, ...args);
}
```

And then use it in your components:

```javascript
import { useLocalStorageState } from './my-hooks';

function Counter() {
  const [count, setCount] = useLocalStorageState('counter', 0);

  // Rest of the component
}
```

## Development

Install development dependencies:

    npm install

To set up the examples:

    npm run examples:setup

To start a server with the examples in watch mode (reloads whenever examples or library code change):

    npm run examples:watch

### Tests

Run tests:

    npm test

Run tests in watch mode:

    npm run test:watch

See code coverage information:

    npm run test:coverage

### Publish

Go to the `master` branch:

    git checkout master

Bump the version number:

    npm version [major | minor | patch]

Run the release script:

    npm run release

All code quality checks will run, the tagged commit generated by `npm version` will be pushed and [Travis CI](https://travis-ci.com/github/soyguijarro/react-storage-hooks) will publish the new package version to the npm registry.

## License

This library is [MIT licensed](LICENSE).


================================================
FILE: examples/.storybook/main.js
================================================
module.exports = {
  stories: ['../src/**/*.stories.tsx'],
  addons: ['@storybook/preset-create-react-app'],
};


================================================
FILE: examples/package.json
================================================
{
  "private": true,
  "scripts": {
    "start": "start-storybook -p 9009 -s public --ci",
    "build": "build-storybook -s public"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "devDependencies": {
    "@storybook/preset-create-react-app": "^2.1.1",
    "@storybook/react": "^5.3.18",
    "@types/react": "^16.9.34",
    "@types/react-dom": "^16.9.6",
    "react": "^16.13.1",
    "react-dom": "^16.13.1",
    "react-scripts": "^3.4.1",
    "typescript": "^3.8.3"
  }
}


================================================
FILE: examples/src/Examples.stories.tsx
================================================
import React from 'react';

import { useStorageState, useStorageReducer } from 'react-storage-hooks';

export function StateCounter() {
  const [count, setCount, writeError] = useStorageState(
    localStorage,
    'state-counter',
    0
  );

  return (
    <>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>+</button>
      <button onClick={() => setCount(count - 1)}>-</button>
      {writeError && (
        <pre>Cannot write to localStorage: {writeError.message}</pre>
      )}
    </>
  );
}

function reducer(state: { count: number }, action: { type: 'inc' | 'dec' }) {
  switch (action.type) {
    case 'inc':
      return { count: state.count + 1 };
    case 'dec':
      return { count: state.count - 1 };
    default:
      return state;
  }
}

export function ReducerCounter() {
  const [state, dispatch, writeError] = useStorageReducer(
    localStorage,
    'reducer-counter',
    reducer,
    { count: 0 }
  );

  return (
    <>
      <p>You clicked {state.count} times</p>
      <button onClick={() => dispatch({ type: 'inc' })}>+</button>
      <button onClick={() => dispatch({ type: 'dec' })}>-</button>
      {writeError && (
        <pre>Cannot write to localStorage: {writeError.message}</pre>
      )}
    </>
  );
}

export default { title: 'Examples' };


================================================
FILE: examples/src/react-app-env.d.ts
================================================
/// <reference types="react-scripts" />


================================================
FILE: examples/tsconfig.json
================================================
{
  "compilerOptions": {
    "target": "es5",
    "lib": [
      "dom",
      "dom.iterable",
      "esnext"
    ],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "react"
  },
  "include": [
    "src"
  ]
}


================================================
FILE: package.json
================================================
{
  "name": "react-storage-hooks",
  "version": "4.0.1",
  "description": "React hooks for persistent state",
  "keywords": [
    "react",
    "react-hooks",
    "persistent",
    "useState",
    "useReducer",
    "storage",
    "localstorage",
    "sessionstorage"
  ],
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
  "scripts": {
    "lint": "eslint src/*.ts",
    "fmt": "prettier --check *.md *.json src/*.ts",
    "types": "tsd",
    "test": "jest",
    "test:watch": "npm test -- --watch",
    "test:coverage": "npm test -- --coverage",
    "test:staged": "npm test -- --findRelatedTests --bail",
    "prebuild": "del dist",
    "build": "tsc",
    "build:watch": "npm run build -- --watch",
    "size": "size-limit",
    "precheck": "npm run build",
    "check": "run-s lint fmt types test:coverage size",
    "examples:setup": "cd examples && npm install && npm link ../.",
    "examples:start": "cd examples && npm start",
    "examples:watch": "run-p build:watch examples:start",
    "prerelease": "npm run check",
    "release": "git push --follow-tags origin master"
  },
  "files": [
    "dist",
    "dist/index.d.ts"
  ],
  "author": "Ramón Guijarro <hola@soyguijarro.com>",
  "license": "MIT",
  "repository": "https://github.com/soyguijarro/react-storage-hooks",
  "peerDependencies": {
    "react": "^16.8.0"
  },
  "husky": {
    "hooks": {
      "pre-commit": "lint-staged"
    }
  },
  "prettier": {
    "singleQuote": true
  },
  "eslintConfig": {
    "parser": "@typescript-eslint/parser",
    "plugins": [
      "@typescript-eslint",
      "react-hooks"
    ],
    "extends": [
      "plugin:@typescript-eslint/recommended",
      "plugin:react-app/recommended",
      "prettier",
      "prettier/@typescript-eslint"
    ],
    "rules": {
      "no-console": "error",
      "react-hooks/rules-of-hooks": "error",
      "react-hooks/exhaustive-deps": "error",
      "@typescript-eslint/explicit-function-return-type": "off"
    },
    "settings": {
      "react": {
        "version": "detect"
      }
    }
  },
  "lint-staged": {
    "*.{md,json}": "prettier --write",
    "*.ts": [
      "prettier --write",
      "eslint --fix",
      "npm run test:staged"
    ]
  },
  "jest": {
    "moduleFileExtensions": [
      "ts",
      "js"
    ],
    "preset": "ts-jest",
    "testMatch": [
      "**/src/tests/*.test.ts"
    ],
    "coveragePathIgnorePatterns": [
      "/node_modules/",
      "<rootDir>/src/tests/"
    ],
    "coverageThreshold": {
      "global": {
        "branches": 100,
        "functions": 100,
        "lines": 100,
        "statements": 100
      }
    }
  },
  "tsd": {
    "directory": "src"
  },
  "size-limit": [
    {
      "limit": "700 B",
      "path": "dist/index.js"
    }
  ],
  "devDependencies": {
    "@size-limit/preset-small-lib": "^4.4.5",
    "@testing-library/react-hooks": "^3.2.1",
    "@types/jest": "^25.2.1",
    "@types/react": "^16.9.34",
    "@typescript-eslint/eslint-plugin": "^2.28.0",
    "@typescript-eslint/parser": "^2.28.0",
    "del-cli": "^3.0.0",
    "eslint": "^6.8.0",
    "eslint-config-prettier": "^6.10.1",
    "eslint-plugin-react-app": "^6.2.2",
    "eslint-plugin-react-hooks": "^3.0.0",
    "husky": "^4.2.5",
    "jest": "^25.3.0",
    "lint-staged": "^10.1.5",
    "npm-run-all": "^4.1.5",
    "prettier": "^2.0.4",
    "react": "^16.13.1",
    "react-test-renderer": "^16.13.1",
    "size-limit": "^4.4.5",
    "ts-jest": "^25.4.0",
    "tsd": "^0.11.0",
    "typescript": "^3.8.3"
  }
}


================================================
FILE: src/common.ts
================================================
import { useState, useEffect, useRef, useMemo } from 'react';

export type StorageObj = Pick<Storage, 'getItem' | 'setItem' | 'removeItem'>;

function fromStorage<T>(value: string | null) {
  return value !== null ? (JSON.parse(value) as T) : null;
}

function readItem<T>(storage: StorageObj, key: string) {
  try {
    const storedValue = storage.getItem(key);
    return fromStorage<T>(storedValue);
  } catch (e) {
    return null;
  }
}

function toStorage<T>(value: T | null) {
  return JSON.stringify(value);
}

function writeItem<T>(storage: StorageObj, key: string, value: T | null) {
  try {
    if (value !== null) {
      storage.setItem(key, toStorage<T>(value));
    } else {
      storage.removeItem(key);
    }
    return Promise.resolve();
  } catch (error) {
    return Promise.reject(error);
  }
}

export function useInitialState<S>(
  storage: StorageObj,
  key: string,
  defaultState: S
) {
  const defaultStateRef = useRef(defaultState);

  return useMemo(() => readItem<S>(storage, key) ?? defaultStateRef.current, [
    key,
    storage,
  ]);
}

export function useStorageWriter<S>(
  storage: StorageObj,
  key: string,
  state: S
) {
  const [writeError, setWriteError] = useState<Error | undefined>(undefined);

  useEffect(() => {
    writeItem<S>(storage, key, state).catch((error) => {
      if (!error || !error.message || error.message !== writeError?.message) {
        setWriteError(error);
      }
    });

    if (writeError) {
      return () => {
        setWriteError(undefined);
      };
    }
  }, [state, key, writeError, storage]);

  return writeError;
}

export function useStorageListener<S>(
  storage: StorageObj,
  key: string,
  defaultState: S,
  onChange: (newValue: S) => void
) {
  const defaultStateRef = useRef(defaultState);
  const onChangeRef = useRef(onChange);

  const firstRun = useRef(true);
  useEffect(() => {
    if (firstRun.current) {
      firstRun.current = false;
      return;
    }

    onChangeRef.current(readItem<S>(storage, key) ?? defaultStateRef.current);
  }, [key, storage]);

  useEffect(() => {
    function onStorageChange(event: StorageEvent) {
      if (event.key === key) {
        onChangeRef.current(
          fromStorage<S>(event.newValue) ?? defaultStateRef.current
        );
      }
    }

    if (
      typeof window !== 'undefined' &&
      typeof window.addEventListener !== 'undefined'
    ) {
      window.addEventListener('storage', onStorageChange);
      return () => {
        window.removeEventListener('storage', onStorageChange);
      };
    }
  }, [key]);
}


================================================
FILE: src/index.ts
================================================
export { default as useStorageState } from './state';
export { default as useStorageReducer } from './reducer';


================================================
FILE: src/reducer.ts
================================================
import { useReducer, Reducer, Dispatch } from 'react';

import {
  useInitialState,
  useStorageListener,
  useStorageWriter,
  StorageObj,
} from './common';

const FORCE_STATE_ACTION = '__FORCE_STATE_INTERNAL_API__';
type ForceStateAction<S> = { type: typeof FORCE_STATE_ACTION; payload: S };

function isForceStateAction<S, A>(
  action: A | ForceStateAction<S>
): action is ForceStateAction<S> {
  return (
    typeof action === 'object' &&
    action !== null &&
    'type' in action &&
    action.type === FORCE_STATE_ACTION
  );
}

function addForceStateActionToReducer<S, A>(reducer: Reducer<S, A>) {
  return (state: S, action: A | ForceStateAction<S>) => {
    if (isForceStateAction(action)) return action.payload;
    return reducer(state, action);
  };
}

function useStorageReducer<S, A>(
  storage: StorageObj,
  key: string,
  reducer: Reducer<S, A>,
  defaultState: S
): [S, Dispatch<A>, Error | undefined];

function useStorageReducer<S, A, I>(
  storage: StorageObj,
  key: string,
  reducer: Reducer<S, A>,
  defaultInitialArg: I,
  defaultInit: (defaultInitialArg: I) => S
): [S, Dispatch<A>, Error | undefined];

function useStorageReducer<S, A, I = S>(
  storage: StorageObj,
  key: string,
  reducer: Reducer<S, A>,
  defaultInitialArg: I,
  defaultInit: (defaultInitialArg: I | S) => S = (x) => x as S
): [S, Dispatch<A>, Error | undefined] {
  const defaultState = defaultInit(defaultInitialArg);

  const [state, dispatch] = useReducer(
    addForceStateActionToReducer(reducer),
    useInitialState(storage, key, defaultState)
  );

  useStorageListener(storage, key, defaultState, (newValue: S) => {
    dispatch({ type: FORCE_STATE_ACTION, payload: newValue });
  });
  const writeError = useStorageWriter(storage, key, state);

  return [state, dispatch, writeError];
}

export default useStorageReducer;


================================================
FILE: src/state.ts
================================================
import { useState, Dispatch, SetStateAction } from 'react';

import {
  useInitialState,
  useStorageListener,
  useStorageWriter,
  StorageObj,
} from './common';

function useStorageState<S>(
  storage: StorageObj,
  key: string,
  defaultState: S | (() => S)
): [S, Dispatch<SetStateAction<S>>, Error | undefined];

function useStorageState<S>(
  storage: StorageObj,
  key: string
): [S | null, Dispatch<SetStateAction<S | null>>, Error | undefined];

function useStorageState<S>(
  storage: StorageObj,
  key: string,
  defaultState: S | (() => S) | null = null
) {
  const [state, setState] = useState(
    useInitialState(storage, key, defaultState)
  );

  useStorageListener(storage, key, defaultState, setState);
  const writeError = useStorageWriter(storage, key, state);

  return [state, setState, writeError];
}

export default useStorageState;


================================================
FILE: src/tests/reducer.node.test.ts
================================================
/**
 * @jest-environment node
 */

import { renderHook } from '@testing-library/react-hooks';

import { useStorageReducer } from '..';
import { storageLikeObject } from './utils';

function reducer(state: { value: number }) {
  return state;
}

it('returns default state', () => {
  const { result } = renderHook(() =>
    useStorageReducer(storageLikeObject, 'key', reducer, {
      value: 0,
    })
  );

  const [state] = result.current;
  expect(state).toStrictEqual({ value: 0 });
});

it('returns default state (lazy initialization)', () => {
  const { result } = renderHook(() =>
    useStorageReducer(storageLikeObject, 'key', reducer, 0, value => ({
      value,
    }))
  );

  const [state] = result.current;
  expect(state).toStrictEqual({ value: 0 });
});


================================================
FILE: src/tests/reducer.test-d.ts
================================================
/* eslint-disable react-hooks/rules-of-hooks */

import { Dispatch } from 'react';
import { expectType, expectError } from 'tsd';

import { useStorageReducer } from '..';
import { storageLikeObject } from './utils';

type State = { value: number };
type Action = { type: 'inc' | 'dec' };

function reducer(state: State, action: Action) {
  switch (action.type) {
    case 'inc':
      return { value: state.value + 1 };
    case 'dec':
      return { value: state.value - 1 };
    default:
      return state;
  }
}

const [state, dispatch, writeError] = useStorageReducer(
  localStorage,
  'key',
  reducer,
  { value: 0 }
);
expectType<State>(state);
expectType<Dispatch<Action>>(dispatch);
expectType<Error | undefined>(writeError);
expectError(() => dispatch({ type: 'other' }));

const [otherState, otherDispatch] = useStorageReducer(
  localStorage,
  'key',
  reducer,
  0,
  value => ({ value })
);
expectType<State>(otherState);
expectType<Dispatch<Action>>(otherDispatch);

useStorageReducer(storageLikeObject, 'key', reducer, { value: 0 });

expectError(() => useStorageReducer());
expectError(() => useStorageReducer(localStorage));
expectError(() => useStorageReducer(localStorage, 'key'));
expectError(() => useStorageReducer(localStorage, 'key', reducer));

expectError(() => useStorageReducer({}, 'key', reducer, { value: 0 }));
expectError(() => useStorageReducer(localStorage, 0, reducer, { value: 0 }));
expectError(() =>
  useStorageReducer(localStorage, 'key', () => 0, { value: 0 })
);
expectError(() =>
  useStorageReducer(localStorage, 'key', reducer, { value: 'value' })
);
expectError(() =>
  useStorageReducer(localStorage, 'key', reducer, 'value', value => ({ value }))
);


================================================
FILE: src/tests/reducer.test.ts
================================================
import { renderHook, act } from '@testing-library/react-hooks';

import { useStorageReducer } from '..';
import {
  mockStorageError,
  mockStorageErrorOnce,
  fireStorageEvent,
} from './utils';

afterEach(() => {
  localStorage.clear();
  jest.restoreAllMocks();
});

function reducer(state: { value: number }, action: { type: 'inc' | 'dec' }) {
  switch (action.type) {
    case 'inc':
      return { value: state.value + 1 };
    case 'dec':
      return { value: state.value - 1 };
    default:
      return state;
  }
}

describe('initialization', () => {
  it('returns storage value when available', () => {
    localStorage.setItem('key', '{"value":1}');

    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, {
        value: 0,
      })
    );

    const [state] = result.current;
    expect(state).toStrictEqual({ value: 1 });
  });

  it('returns default state when storage empty and writes it to storage', () => {
    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );

    const [state] = result.current;
    expect(state).toStrictEqual({ value: 0 });
    expect(localStorage.getItem('key')).toBe('{"value":0}');
  });

  it('returns default state when storage empty and writes it to storage (lazy initialization)', () => {
    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, 0, value => ({ value }))
    );

    const [state] = result.current;
    expect(state).toStrictEqual({ value: 0 });
    expect(localStorage.getItem('key')).toBe('{"value":0}');
  });

  it('returns default state when storage reading fails', () => {
    mockStorageErrorOnce(localStorage, 'getItem', 'Error message');
    localStorage.setItem('key', '{"value":1}');

    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );

    const {
      current: [state],
    } = result;
    expect(state).toStrictEqual({ value: 0 });
  });
});

describe('updates', () => {
  it('returns new state and writes to storage', () => {
    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );
    const [, dispatch] = result.current;
    act(() => dispatch({ type: 'inc' }));

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
    expect(localStorage.getItem('key')).toBe('{"value":1}');
  });

  it('returns new state and write error when storage writing fails once', async () => {
    mockStorageErrorOnce(localStorage, 'setItem', 'Error message');

    const { result, waitForNextUpdate } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );
    const [, dispatch] = result.current;
    act(() => dispatch({ type: 'inc' }));
    await waitForNextUpdate();

    const [newState, , writeError] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
    expect(writeError).toEqual(Error('Error message'));
  });

  it('returns new state and previous write error when storage writing fails multiple times', async () => {
    mockStorageError(localStorage, 'setItem', 'Error message');

    const { result, waitForNextUpdate } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );
    const [, dispatch] = result.current;
    act(() => dispatch({ type: 'inc' }));
    await waitForNextUpdate();

    const [, newDispatch, writeError] = result.current;
    expect(writeError).toEqual(Error('Error message'));

    act(() => newDispatch({ type: 'inc' }));
    await waitForNextUpdate();

    const [, , newWriteError] = result.current;
    expect(newWriteError).toEqual(Error('Error message'));
  });

  it('returns new state and no previous write error when storage writing works after failing', async () => {
    mockStorageErrorOnce(localStorage, 'setItem', 'Error message');

    const { result, waitForNextUpdate } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );
    const [, dispatch] = result.current;
    act(() => dispatch({ type: 'inc' }));
    await waitForNextUpdate();

    const [, newDispatch, writeError] = result.current;
    expect(writeError).toEqual(Error('Error message'));

    act(() => newDispatch({ type: 'inc' }));

    const [, , newWriteError] = result.current;
    expect(newWriteError).toBeUndefined();
  });

  it('returns same state when default state changes', () => {
    localStorage.setItem('key', '{"value":1}');

    const { result, rerender } = renderHook(
      defaultState =>
        useStorageReducer(localStorage, 'key', reducer, defaultState),
      { initialProps: { value: 0 } }
    );
    rerender({ value: 2 });

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
  });

  it('returns same state when storage empty and default state changes', () => {
    const { result, rerender } = renderHook(
      defaultState =>
        useStorageReducer(localStorage, 'key', reducer, defaultState),
      { initialProps: { value: 0 } }
    );
    rerender({ value: 1 });

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });

  it('returns new state when storage event fired for key', () => {
    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );

    act(() => fireStorageEvent('key', '{"value":1}'));

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
  });

  it('returns same state when storage event fired for key and storage empty', () => {
    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );

    act(() => fireStorageEvent('key', null));

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });

  it('returns same state when storage event fired for other key', () => {
    const { result } = renderHook(() =>
      useStorageReducer(localStorage, 'key', reducer, { value: 0 })
    );

    act(() => {
      fireStorageEvent('other-key', '{"value":1}');
    });

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });
});

describe('resetting', () => {
  it('returns new storage value when key changes and storage value available', () => {
    localStorage.setItem('new-key', '{"value":1}');

    const { result, rerender } = renderHook(
      key => useStorageReducer(localStorage, key, reducer, { value: 0 }),
      {
        initialProps: 'key',
      }
    );
    rerender('new-key');

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
  });

  it('returns default state when key changes and storage empty', () => {
    localStorage.setItem('key', '{"value":1}');

    const { result, rerender } = renderHook(
      key => useStorageReducer(localStorage, key, reducer, { value: 0 }),
      {
        initialProps: 'key',
      }
    );
    rerender('new-key');

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });

  it('returns no previous write error when key changes', async () => {
    mockStorageErrorOnce(localStorage, 'setItem', 'Error message');

    const { result, rerender, waitForNextUpdate } = renderHook(
      key => useStorageReducer(localStorage, key, reducer, { value: 0 }),
      { initialProps: 'key' }
    );
    const [, dispatch] = result.current;
    act(() => dispatch({ type: 'inc' }));
    await waitForNextUpdate();

    const [, , writeError] = result.current;
    expect(writeError).toEqual(Error('Error message'));

    rerender('new-key');

    const [, , newWriteError] = result.current;
    expect(newWriteError).toBeUndefined();
  });

  it('writes to new key when key changes', () => {
    localStorage.setItem('key', '{"value":1}');
    localStorage.setItem('new-key', '{"value":2}');

    const { result, rerender } = renderHook(
      key => useStorageReducer(localStorage, key, reducer, { value: 0 }),
      {
        initialProps: 'key',
      }
    );
    rerender('new-key');
    const [, dispatch] = result.current;
    act(() => dispatch({ type: 'inc' }));

    expect(localStorage.getItem('key')).toStrictEqual('{"value":1}');
    expect(localStorage.getItem('new-key')).toStrictEqual('{"value":3}');
  });
});


================================================
FILE: src/tests/state.node.test.ts
================================================
/**
 * @jest-environment node
 */

import { renderHook } from '@testing-library/react-hooks';

import { useStorageState } from '..';
import { storageLikeObject } from './utils';

it('returns default state', () => {
  const { result } = renderHook(() =>
    useStorageState(storageLikeObject, 'key', { value: 0 })
  );
  const [state] = result.current;
  expect(state).toStrictEqual({ value: 0 });
});

it('returns default state (lazy initialization)', () => {
  const { result } = renderHook(() =>
    useStorageState(storageLikeObject, 'key', () => ({ value: 0 }))
  );

  const [state] = result.current;
  expect(state).toStrictEqual({ value: 0 });
});


================================================
FILE: src/tests/state.test-d.ts
================================================
/* eslint-disable react-hooks/rules-of-hooks */

import { Dispatch, SetStateAction } from 'react';
import { expectType, expectError } from 'tsd';

import { useStorageState } from '..';
import { storageLikeObject } from './utils';

type SetState<S> = Dispatch<SetStateAction<S>>;

const [inferredString, setInferredString, writeError] = useStorageState(
  localStorage,
  'key',
  'test'
);
expectType<string>(inferredString);
expectType<SetState<string>>(setInferredString);
expectType<Error | undefined>(writeError);
expectError(() => setInferredString(0));

const [inferredNumber, setInferredNumber] = useStorageState(
  localStorage,
  'key',
  0
);
expectType<number>(inferredNumber);
expectType<SetState<number>>(setInferredNumber);
expectError(() => setInferredNumber('test'));

const [inferredNumberLazy, setInferredNumberLazy] = useStorageState(
  localStorage,
  'key',
  () => 0
);
expectType<number>(inferredNumberLazy);
expectType<SetState<number>>(setInferredNumberLazy);
expectError(() => setInferredNumberLazy('test'));

const [declaredNumber, setDeclaredNumber] = useStorageState<number>(
  localStorage,
  'key'
);
expectType<number | null>(declaredNumber);
expectType<SetState<number | null>>(setDeclaredNumber);
expectError(() => setDeclaredNumber('test'));

const [unknown, setUnknown] = useStorageState(localStorage, 'key');
expectType<unknown>(unknown);
expectType<SetState<unknown>>(setUnknown);

useStorageState(storageLikeObject, 'key', 0);

expectError(() => useStorageState());
expectError(() => useStorageState(localStorage));

expectError(() => useStorageState({}, 'key'));
expectError(() => useStorageState(localStorage, 0));


================================================
FILE: src/tests/state.test.ts
================================================
import { renderHook, act } from '@testing-library/react-hooks';

import { useStorageState } from '..';
import {
  mockStorageError,
  mockStorageErrorOnce,
  fireStorageEvent,
} from './utils';

afterEach(() => {
  localStorage.clear();
  jest.restoreAllMocks();
});

describe('initialization', () => {
  it('returns storage value when available', () => {
    localStorage.setItem('key', '{"value":1}');

    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );

    const [state] = result.current;
    expect(state).toStrictEqual({ value: 1 });
  });

  it('returns default state when storage empty and writes it to storage', () => {
    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );

    const [state] = result.current;
    expect(state).toStrictEqual({ value: 0 });
    expect(localStorage.getItem('key')).toBe('{"value":0}');
  });

  it('returns default state when storage empty and writes it to storage (lazy initialization)', () => {
    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', () => ({ value: 0 }))
    );

    const [state] = result.current;
    expect(state).toStrictEqual({ value: 0 });
    expect(localStorage.getItem('key')).toBe('{"value":0}');
  });

  it('returns null when storage empty and no default provided', () => {
    const { result } = renderHook(() => useStorageState(localStorage, 'key'));

    const [state] = result.current;
    expect(state).toBeNull();
  });

  it('returns default state when storage reading fails', () => {
    mockStorageErrorOnce(localStorage, 'getItem', 'Error message');
    localStorage.setItem('key', '{"value":1}');

    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );

    const {
      current: [state],
    } = result;
    expect(state).toStrictEqual({ value: 0 });
  });

  it('returns null when storage reading fails and no default provided', () => {
    mockStorageErrorOnce(localStorage, 'getItem', 'Error message');
    localStorage.setItem('key', '{"value":1}');

    const { result } = renderHook(() => useStorageState(localStorage, 'key'));

    const {
      current: [state],
    } = result;
    expect(state).toBeNull();
  });
});

describe('updates', () => {
  it('returns new state and writes to storage', () => {
    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );
    const [, setState] = result.current;
    act(() => setState({ value: 1 }));

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
    expect(localStorage.getItem('key')).toBe('{"value":1}');
  });

  it('returns new state and write error when storage writing fails once', async () => {
    mockStorageErrorOnce(localStorage, 'setItem', 'Error message');

    const { result, waitForNextUpdate } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );
    const [, setState] = result.current;
    act(() => setState({ value: 1 }));
    await waitForNextUpdate();

    const [newState, , writeError] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
    expect(writeError).toEqual(Error('Error message'));
  });

  it('returns new state and previous write error when storage writing fails multiple times', async () => {
    mockStorageError(localStorage, 'setItem', 'Error message');

    const { result, waitForNextUpdate } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );
    const [, setState] = result.current;
    act(() => setState({ value: 1 }));
    await waitForNextUpdate();

    const [, newSetState, writeError] = result.current;
    expect(writeError).toEqual(Error('Error message'));

    act(() => newSetState({ value: 2 }));
    await waitForNextUpdate();

    const [, , newWriteError] = result.current;
    expect(newWriteError).toEqual(Error('Error message'));
  });

  it('returns new state and no previous write error when storage writing works after failing', async () => {
    mockStorageErrorOnce(localStorage, 'setItem', 'Error message');

    const { result, waitForNextUpdate } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );
    const [, setState] = result.current;
    act(() => setState({ value: 1 }));
    await waitForNextUpdate();

    const [, newSetState, writeError] = result.current;
    expect(writeError).toEqual(Error('Error message'));

    act(() => newSetState({ value: 2 }));

    const [, , newWriteError] = result.current;
    expect(newWriteError).toBeUndefined();
  });

  it('returns same state when default state changes', () => {
    localStorage.setItem('key', '{"value":1}');

    const { result, rerender } = renderHook(
      defaultState => useStorageState(localStorage, 'key', defaultState),
      { initialProps: { value: 0 } }
    );
    rerender({ value: 2 });

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
  });

  it('returns same state when storage empty and default state changes', () => {
    const { result, rerender } = renderHook(
      defaultState => useStorageState(localStorage, 'key', defaultState),
      { initialProps: { value: 0 } }
    );
    rerender({ value: 1 });

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });

  it('returns null and removes key from storage when null provided', () => {
    localStorage.setItem('key', '{"value":1}');

    const { result } = renderHook(() =>
      useStorageState<{ value: number } | null>(localStorage, 'key', {
        value: 0,
      })
    );
    const [, setState] = result.current;
    act(() => setState(null));

    const [newState] = result.current;
    expect(newState).toBeNull();
    expect(localStorage.getItem('key')).toBeNull();
  });

  it('returns new state when storage event fired for key', () => {
    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', 0)
    );

    act(() => fireStorageEvent('key', '{"value":1}'));

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
  });

  it('returns same state when storage event fired for key and storage empty', () => {
    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );

    act(() => fireStorageEvent('key', null));

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });

  it('returns same state when storage event fired for other key', () => {
    const { result } = renderHook(() =>
      useStorageState(localStorage, 'key', { value: 0 })
    );

    act(() => {
      fireStorageEvent('other-key', '{"value":1}');
    });

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });
});

describe('resetting', () => {
  it('returns new storage value when key changes and storage value available', () => {
    localStorage.setItem('new-key', '{"value":1}');

    const { result, rerender } = renderHook(
      key => useStorageState(localStorage, key, { value: 0 }),
      {
        initialProps: 'key',
      }
    );
    rerender('new-key');

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 1 });
  });

  it('returns default state when key changes and storage empty', () => {
    localStorage.setItem('key', '1');

    const { result, rerender } = renderHook(
      key => useStorageState(localStorage, key, { value: 0 }),
      {
        initialProps: 'key',
      }
    );
    rerender('new-key');

    const [newState] = result.current;
    expect(newState).toStrictEqual({ value: 0 });
  });

  it('returns null when key changes, storage empty and no default provided', () => {
    localStorage.setItem('key', '{"value":1}');

    const { result, rerender } = renderHook(
      key => useStorageState(localStorage, key),
      {
        initialProps: 'key',
      }
    );
    rerender('new-key');

    const [newState] = result.current;
    expect(newState).toBeNull();
  });

  it('returns no previous write error when key changes', async () => {
    mockStorageErrorOnce(localStorage, 'setItem', 'Error message');

    const { result, rerender, waitForNextUpdate } = renderHook(
      key => useStorageState(localStorage, key, { value: 0 }),
      { initialProps: 'key' }
    );
    const [, setState] = result.current;
    act(() => setState({ value: 1 }));
    await waitForNextUpdate();

    const [, , writeError] = result.current;
    expect(writeError).toEqual(Error('Error message'));

    rerender('new-key');

    const [, , newWriteError] = result.current;
    expect(newWriteError).toBeUndefined();
  });

  it('writes to new key when key changes', () => {
    localStorage.setItem('key', '{"value":1}');
    localStorage.setItem('new-key', '{"value":2}');

    const { result, rerender } = renderHook(
      key => useStorageState(localStorage, key, { value: 0 }),
      {
        initialProps: 'key',
      }
    );
    rerender('new-key');
    const [, setState] = result.current;
    act(() => setState({ value: 3 }));

    expect(localStorage.getItem('key')).toBe('{"value":1}');
    expect(localStorage.getItem('new-key')).toBe('{"value":3}');
  });
});


================================================
FILE: src/tests/utils.ts
================================================
function getStorageSpy(storage: Storage, method: 'getItem' | 'setItem') {
  // Cannot mock Storage methods directly: https://github.com/facebook/jest/issues/6798
  return jest.spyOn(Object.getPrototypeOf(storage), method);
}

export function mockStorageError(
  storage: Storage,
  method: 'getItem' | 'setItem',
  errorMessage: string
) {
  getStorageSpy(storage, method).mockImplementation(() => {
    throw new Error(errorMessage);
  });
}

export function mockStorageErrorOnce(
  storage: Storage,
  method: 'getItem' | 'setItem',
  errorMessage: string
) {
  getStorageSpy(storage, method).mockImplementationOnce(() => {
    throw new Error(errorMessage);
  });
}

export function fireStorageEvent(key: string, value: string | null) {
  window.dispatchEvent(new StorageEvent('storage', { key, newValue: value }));
}

export const storageLikeObject = {
  getItem: (key: string) => null,
  /* eslint-disable @typescript-eslint/no-empty-function */
  setItem: (key: string, value: string) => {},
  removeItem: (key: string) => {},
  /* eslint-enable @typescript-eslint/no-empty-function */
};


================================================
FILE: tsconfig.json
================================================
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "lib": ["es2016", "dom"],
    "jsx": "react",
    "declaration": true,
    "sourceMap": true,
    "outDir": "./dist/",
    "strict": true,
    "moduleResolution": "node",
    "esModuleInterop": true
  },
  "include": ["src/index.ts"]
}