[
{
"path": "LICENSE",
"content": "GNU GENERAL PUBLIC LICENSE\n Version 2, June 1991\n\n Copyright (C) 1989, 1991 Free Software Foundation, Inc., \n 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA\n Everyone is permitted to copy and distribute verbatim copies\n of this license document, but changing it is not allowed.\n\n Preamble\n\n The licenses for most software are designed to take away your\nfreedom to share and change it. By contrast, the GNU General Public\nLicense is intended to guarantee your freedom to share and change free\nsoftware--to make sure the software is free for all its users. This\nGeneral Public License applies to most of the Free Software\nFoundation's software and to any other program whose authors commit to\nusing it. (Some other Free Software Foundation software is covered by\nthe GNU Lesser General Public License instead.) You can apply it to\nyour programs, too.\n\n When we speak of free software, we are referring to freedom, not\nprice. 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For software which is copyrighted by the Free\nSoftware Foundation, write to the Free Software Foundation; we sometimes\nmake exceptions for this. Our decision will be guided by the two goals\nof preserving the free status of all derivatives of our free software and\nof promoting the sharing and reuse of software generally.\n\n NO WARRANTY\n\n 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY\nFOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN\nOTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES\nPROVIDE THE PROGRAM \"AS IS\" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED\nOR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF\nMERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS\nTO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE\nPROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,\nREPAIR OR CORRECTION.\n\n 12. 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It is safest\nto attach them to the start of each source file to most effectively\nconvey the exclusion of warranty; and each file should have at least\nthe \"copyright\" line and a pointer to where the full notice is found.\n\n {description}\n Copyright (C) {year} {fullname}\n\n This program is free software; you can redistribute it and/or modify\n it under the terms of the GNU General Public License as published by\n the Free Software Foundation; either version 2 of the License, or\n (at your option) any later version.\n\n This program is distributed in the hope that it will be useful,\n but WITHOUT ANY WARRANTY; without even the implied warranty of\n MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the\n GNU General Public License for more details.\n\n You should have received a copy of the GNU General Public License along\n with this program; if not, write to the Free Software Foundation, Inc.,\n 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.\n\nAlso add information on how to contact you by electronic and paper mail.\n\nIf the program is interactive, make it output a short notice like this\nwhen it starts in an interactive mode:\n\n Gnomovision version 69, Copyright (C) year name of author\n Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.\n This is free software, and you are welcome to redistribute it\n under certain conditions; type `show c' for details.\n\nThe hypothetical commands `show w' and `show c' should show the appropriate\nparts of the General Public License. Of course, the commands you use may\nbe called something other than `show w' and `show c'; they could even be\nmouse-clicks or menu items--whatever suits your program.\n\nYou should also get your employer (if you work as a programmer) or your\nschool, if any, to sign a \"copyright disclaimer\" for the program, if\nnecessary. Here is a sample; alter the names:\n\n Yoyodyne, Inc., hereby disclaims all copyright interest in the program\n `Gnomovision' (which makes passes at compilers) written by James Hacker.\n\n {signature of Ty Coon}, 1 April 1989\n Ty Coon, President of Vice\n\nThis General Public License does not permit incorporating your program into\nproprietary programs. If your program is a subroutine library, you may\nconsider it more useful to permit linking proprietary applications with the\nlibrary. If this is what you want to do, use the GNU Lesser General\nPublic License instead of this License.\n\n"
},
{
"path": "README.md",
"content": "# 开发无框架单页面应用 -- 老码农的祖传秘方\n#\n\n## 什么是单页面应用（SPA）？\n[维基百科上的描述](http://en.wikipedia.org/wiki/Single-page_application )是这样的：\n```\n“A single-page application (SPA), is a web application or web site\nthat fits on a single web page with the goal of providing a more\nfluid user experience akin to a desktop application.”\n```\n也就是说，单页面应用是仅包含单个网页的应用，目的是为了提供类似于本地应用的流畅用户体验。\n\n## 需不需要框架？\n要实现单页面应用，现在已经有很多现成的框架了，比如`AngularJS`, `Ember.js`, `Backbone.js`等等。它们都是很全面的开发平台，为单页面应用开发提供了必需的页面模板、路径解析和处理、后台服务api访问、DOM操作等功能。\n\n事实上，现代的web应用开发基本都离不开一个甚至多个框架，开发无框架应用的想法听起来蛮不靠谱的，对吧？\n\n但是我总觉得现在是时候抛弃框架了。前两年我都在用 `AngularJS` 做开发，可以说已经比较熟悉它了，我的第一个单页面应用就是在 `AngularJS` 的启发下做出来的。框架曾经是我的挚爱。\n\n但是现在每次看着它们那庞大臃肿的身躯和晦涩的语法，我都有一种鸡肋的感觉。还有不同框架下各种工具、插件难以混用的现状，让我不得不经常需要自己写原生代码解决很多问题。时间长了，我自然冒出一个想法：“为啥不干脆抛弃框架，直接写原生代码呢？毕竟，框架也是原生代码写出来的嘛。”\n\n## 怎么实现无框架SPA？\n无框架单页面应用看似可行，但难度有多大？我还是心里没底，需要一点理论依据给自己壮胆。所以我就在网上到处寻摸了一番，偶然找到了这篇 Google 工程师 Joe Gregorio 写的文章[《别再用JS框架了》](http://coderlmn.github.io/frontEndCourse/nomoreJSF.html )，里面的分析有一种与我心有戚戚的感觉，看完还给它翻译成中文了。\n\n不过，他提出的方法是更超前的，例如 `imports` 和 `Polymer`，我曾经试过，印象中只有 Google 的 Chrome Canary 才有支持，而且要先在选项中打开一些试验功能，浏览器会变得不那么稳定。`X-Tag` 和 `Bosonic` 也要依赖于一个小的库。而我想做的是现在的浏览器就已经能支持的功能，用原生代码来实现。所以他这篇文章只能让我坚定方向，但是具体的做法还得靠自己去发现。\n\n后来又看了几篇比较偏学术的文章，例如这篇 Mixu 写的[《Single page apps in depth》](http://singlepageappbook.com/single-page.html )，对我也不太适用。他的模板都需要先编译为JS对象存放，和 AngularJS 的方法类似，但我觉得在一个小规模应用里应该有更加优雅的实现方法。\n\n找了好几天文档，我突然意识到自己浪费了不少时间。所谓理论依据应该是高层次的，解决可行性的问题，剩下的就是自己去想办法实现了。可行性不是明摆着的嘛，那么多框架不也是用原生代码实现的么？\n\n想到这儿，我就开始自己尝试了。前后一共只花了两三天时间，写出来一共一两百行JS，就基本解决了问题。其实把代码写完了回顾一下，这些方法都算不上什么创新，都是标准的东西而已。肯定有别人也这么做了，只是我不知道而已吧。\n\n可能有读者看到这儿不耐烦了：`“Talk is cheap. Show me the code.”` 好吧，下面就是代码的描述。\n\n## 老码农的实现方法\n\n### 基础对象\n首先是定义缺省的两个页面片段（缺省页面和出错页面，这两个页面是基础功能，所以放在库里）相关代码，对每个片段对应的 uri（例如 `home`）定义一个同名的对象，里面存放了对应的 html 片段文件路径、初始化方法。\n```javascript\nvar home = {}; //default partial page, which will be loaded initially\nhome.partial = \"lib/home.html\";\nhome.init = function(){ //bootstrap method\n //nothing but static content only to render\n}\n\nvar notfound = {}; //404 page\nnotfound.partial = \"lib/404.html\";\nnotfound.init = function(){\n alert('URL does not exist. please check your code.');\n}\n```\n\n随后是全局变量，包含了 html 片段代码的缓存、局部刷新所在 div 的 DOM 对象和向后端服务请求返回的根数据（`rootScope`，初始化时未出现，在后面的方法中才会用到）：\n```javascript\nvar settings = {}; //global parameters\nsettings.partialCache = {}; //cache for partial pages\nsettings.divDemo = document.getElementById(\"demo\"); //div for loading partials, defined in index.html\n```\n\n### 主程序\n下面就是主程序了，所有的公用方法打包放到一个对象 `miniSPA` 中，这样可以避免污染命名空间：\n```javascript\n// Main Object here\nvar miniSPA = {};\n```\n\n然后是 changeUrl 方法，对应在 `index.html` 中有如下触发定义：\n```html\n\n```\n\n`onhashchange` 是在location.hash发生改变的时候触发的事件，能够通过它获取局部 url 的改变。在 `index.html` 中定义了如下的链接：\n```html\n
Demo Contents:
\n Home (Default)\n POST request\n GET request\n Invalid url\n \n```\n\n每个 uri 都以 `#` 号开头，这样就能被 `onhashchange` 事件抓取到。最后的 div 就是局部刷新的 html 片段嵌入的位置。\n```javascript\nminiSPA.changeUrl = function() { //handle url change\n var url = location.hash.replace('#','');\n if(url === ''){\n url = 'home'; //default page\n }\n if(! window[url]){\n url = \"notfound\";\n }\n miniSPA.ajaxRequest(window[url].partial, 'GET', '',function(status, page){\n if(status == 404){\n url = 'notfound'; //404 page\n miniSPA.ajaxRequest(window[url].partial,'GET','',function(status, page404){\n settings.divDemo.innerHTML = page404;\n miniSPA.initFunc(url); //load 404 controller\n });\n }\n else{\n settings.divDemo.innerHTML = page;\n miniSPA.initFunc(url); //load url controller\n }\n });\n}\n```\n上面的代码先获取改变后的 url，先通过 `window[url]` 找到对应的对象（类似于最上部定义的 `home` 和 `notfound`），如对象不存在（无定义的路径）则转到 `404` 处理，否则通过 `ajaxRequest` 方法获取 `window[url].partial` 中定义的 html 片段并加载到局部刷新的div，并执行 `window[url].init` 初始化方法。\n\n`ajaxRequest` 方法主要是和后端的服务进行交互，通过 `XMLHttpRequest` 发送请求（ `GET` 或 `POST`），如果获取的是 html 片段就把它缓存到 `settings.partialCache[url]` 里，因为 html 片段是相对固定的，每次请求返回的内容不会变化。如果是其他请求（比如向 Github 的 markdown 服务 POST 一个字符串）就不能缓存了。\n```javascript\nminiSPA.ajaxRequest = function(url, method, data, callback) { //load partial page\n if(settings.partialCache[url]){\n callback(200, settings.partialCache[url]);\n }\n else {\n var xmlhttp;\n if(window.XMLHttpRequest){\n xmlhttp = new XMLHttpRequest();\n xmlhttp.open(method, url, true);\n if(method === 'POST'){\n xmlhttp.setRequestHeader(\"Content-type\",\"application/x-www-form-urlencoded\");\n }\n xmlhttp.send(data);\n xmlhttp.onreadystatechange = function(){\n if(xmlhttp.readyState == 4){\n switch(xmlhttp.status) {\n case 404: //if the url is invalid, show the 404 page\n url = 'notfound';\n break;\n default:\n var parts = url.split('.');\n if(parts.length>1 && parts[parts.length-1] == 'html'){ //only cache static html pages\n settings.partialCache[url] = xmlhttp.responseText; //cache partials to improve performance\n }\n }\n callback(xmlhttp.status, xmlhttp.responseText);\n }\n }\n }\n else{\n alert('Sorry, your browser is too old to run this app.')\n callback(404, {});\n }\n }\n}\n```\n对于不支持 `XMLHttpRequest` 的浏览器（主要是 IE 老版本），本来是可以在 else 里加上 **xmlhttp = new ActiveXObject('Microsoft.XMLHTTP');** 的，不过，我手头也没有那么多老版本 IE 用于测试，而且老版本 IE 本来就是我深恶痛绝的东西，凭什么要支持它啊？所以就干脆直接给个 `alert` 完事。\n\n\n`render` 方法一般在每个片段的初始化方法中调用，它会设定全局变量中的根对象，并通过 `refresh` 方法渲染 html 片段。\n```javascript\nminiSPA.render = function(url){\n settings.rootScope = window[url];\n miniSPA.refresh(settings.divDemo, settings.rootScope);\n}\n```\n\n获取后端数据后，如何渲染 html 片段是个比较复杂的问题。这就是 DOM 操作了。总体思想就是从 html 片段的根部入手，遍历 DOM 树，逐个替换属性和文本中的占位变量（例如`` 和 `