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<h1 class="title">使用 gulp 搭建CommonJs & ES6 模块化环境</h1>
<section class="info">
<span class="avatar" style="background-image: url(https://joe-10005639.cossh.myqcloud.com/jkbb.jpg);"></span> <a class="name" href="javascript:;">江矿叔叔.</a>
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<article class="content"><h1>1. Browserify简介</h1>
<blockquote>
<p>“Browserify lets you require(‘modules’) in the browser by bundling up all of your dependencies.” - Browserify.org</p>
</blockquote>
<p>上面的描述是摘自 browserify 官网；用通俗的话讲就是：browserify 是一个浏览器端代码模块化工具，可以处理模块之间的依赖关系，让服务器端的 CommonJS 格式的模块可以运行在浏览器端。</p>
<p><img src="data:image/gif;base64,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" data-src="https://cloud.githubusercontent.com/assets/3995814/11768221/b22531fe-a200-11e5-8e98-8e36d8471bf8.png" alt="" /></p>
<p>browserify的原理：</p>
<ul>
<li>处理代码依赖，将模块打包到一起</li>
</ul>
<p>打包为单个文件存在的问题：</p>
<ul>
<li><p>暂时用不到的代码也会被打包，体积大，首次加载速度慢</p></li>
<li><p>只要一个模块更新，整个文件缓存失效</p></li>
</ul>
<p>注：暂时用不到的代码指不同的页面有不同的 JS 文件，不需要在当前页面引用其他页面的代码即为暂时用不到的代码</p>
<p>Browserify的解决方案：</p>
<ul>
<li>entry point：入口点技术，每个入口点打包一个文件，两个入口点的相同依赖模块单独打包为common.js</li>
</ul>
<h3>安装与配置</h3>
<p>安装 browserify</p>
<p><code>npm install -g browserify</code></p>
<p>引入 browserify</p>
<p><code>import browserify from 'browserify'</code></p>
<p>基本配置</p>
<pre><code class="language-js">glup.taks('browserify', function() {
browserify({
//先处理依赖，入口文件
entries: ['./foo.js','./main.js'],
//进行转化
transform: []
})
.bundle() // 多个文件打包成一个文件
.pipe(source()) // browserify的输出不能直接用做gulp输入，所以需要source进行处理
.pipe(gulp.dest('./'));
})
</code></pre>
<h3>安装一些依赖插件</h3>
<pre><code class="language-bash">npm install --save-dev vinyl-source-stream vinyl-buffer gulp-sourcemaps
</code></pre>
<p><code>vinyl-source-stream</code>: browserify的输出不能直接用着gulp的输入，vinly-source-stream 主要是做一个转化</p>
<p><code>vinyl-buffer</code>: 用于将vinyl流转化为buffered vinyl文件（gulp-sourcemaps及大部分Gulp插件都需要这种格式）</p>
<p><code>gulp-sourcemaps</code>: Source map就是一个信息文件，里面储存着位置信息。也就是说，转换后的代码的每一个位置，所对应的转换前的位置，便于调试</p>
<p><code>Watchify</code>: 加速 browserify 编译</p>
<h1>2. 编写 CommonJS 模块</h1>
<h3>目录结构</h3>
<pre><code>|-- dist/
|-----bundle.js
|-- src/
|-----foo.js
|-----main.js
|--gulpfile.babel.js
|--package.json
</code></pre>
<h3>新建两个模块文件 foo.js, main.js</h3>
<p><code>$ touch foo.js main.js</code></p>
<h3>让我使用 CommonJs 规范来写一些代码</h3>
<blockquote>
<p>CommonJS 规范是为了解决 JavaScript的作用域问题而定义的模块形式，可以使每个模块在它自身的命名空间中执行。
该规范的主要内容是，模块必须通过module.exports 导出对外的变量或接口，通过 require() 来导入其他模块的输出到当前模块作用域中。</p>
</blockquote>
<pre><code class="language-js">// foo.js
// 定义foo.js模块，通过 module.exports 导出对外的变量或接口
let variable = 8;
let sum = (a, b = 6) => (a + b);
let square = (b) => {
return b * b;
};
module.exports.variable = variable;
module.exports.sum = sum;
module.exports.square = square;
// mian.js
// 通过 require() 来导入 foo.js 模块
var bar = require('./foo')
console.log(bar); // Object
console.log(bar.variable); // 8
console.log(bar.sum(1)); // 7
console.log(bar.square(5)); // 25
</code></pre>
<blockquote>
<p>上面我们使用 ES6 的语法写了两个模块，分别是 foo.js 和 main.js; 在 foo.js 中通过 module.exports 导出对外的变量或接口;在 main.js 中通过 require() 来导入 foo.js 模块，那我们就可以在 mian.js 模块中使用 foo.js 中的变量和接口了。这就是一个最基本的 CommonJs 示例了</p>
</blockquote>
<h3>配置 browserify</h3>
<p>通过第一小节的学习，我们知道要在浏览器中运行 CommonJs 风格的模块代码，就需要借助 browserify 来作为转换工具，下面我们在 gulp.babel.js 中来配置 browserify：</p>
<pre><code class="language-js">// set browserify task
gulp.task('browserify',()=> {
browserify({
entries: ['src/js/main.js','src/js/foo.js'],
debug: true, // 告知Browserify在运行同时生成内联sourcemap用于调试
})
.transform("babelify", {presets: ["es2015"]})
.bundle()
.pipe(source('bundle.js'))
.pipe(buffer()) // 缓存文件内容
.pipe(sourcemaps.init({loadMaps: true})) // 从 browserify 文件载入 map
.pipe(sourcemaps.write('.')) // 写入 .map 文件
.pipe(gulp.dest('dist/js'))
.pipe(notify({ message: 'browserify task complete' }));
})
</code></pre>
<p>运行
<code>gulp-browserify</code></p>
<p><img src="data:image/gif;base64,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" data-src="https://cloud.githubusercontent.com/assets/3995814/11768266/592159dc-a202-11e5-8be3-2d4ddaefe5c3.png" alt="" /></p>
<h3>打开浏览器，查看运行结果(见上面main.js文件的注释)</h3>
<h1>编写 ES6 Module 模块</h1>
<p>上面的代码主要是 CommonJs 模块化的写法，我们再来看看最近火热的 ES6 提供的 Module；让我们使用 ES6 Module 来改写上面的代码：</p>
<pre><code class="language-js">// foo.js
// 定义foo.js模块，通过 exports 导出对外的变量或接口
let variable = 8;
let sum = (a, b = 6) => (a + b);
let square = (b) => {
return b * b;
};
export { variable, sum, square };
// main.js
// 测试一：
// 通过 import 来导入 foo.js 模块
import {variable, sum, square} from './foo';
console.log(variable); // 8
console.log(sum(1)); // 7
console.log(square(5)); // 25
// 测试二：
// 直接引用整个 foo 模块
import bar from './foo';
console.log(bar); // 输出值是undefined，后面做解释
// 测试三：
// 通过 ES6 的语法加载整个 foo模块
import * as bar from './foo'
console.log(bar); // Object
</code></pre>
<h2>总结 CommonJs 和 ES6 Module</h2>
<h3>CommonJs</h3>
<ul>
<li>根据 CommonJS 规范，一个单独的文件就是一个模块。每一个模块都是一个单独的作用域，也就是说，在一个文件定义的变量（包括函数和类），都是私有的，对其他文件是不可见的</li>
<li>通过 module.exports 对象，定义对外接口，其他文件加载该模块，实际上就是读取 module.exports 变量</li>
<li><p>通过 require 命令加载模块文件，然后返回该模块的exports对象</p>
<h3>ES6 Module</h3></li>
<li><p>通过 export 命令用于规定模块的对外接口</p></li>
<li><p>通过 import 命令用于加载其他模块提供的功能</p>
<h3>ES6 Module 与 CommonJs 的区别</h3></li>
<li><p>在ES6中使用 import 取代 require</p></li>
<li><p>在ES6中使用 export 取代 module.exports</p></li>
<li><p>ES6 在编译时就能确定模块的依赖关系，以及输入和输出的变量，而 CommonJs 只能在运行时确定模块的依赖关系以及输入和输出的变量。</p></li>
<li><p>运行时加载: CommonJS 模块就是对象；即在输入时是先加载整个模块，生成一个对象，然后再从这个对象上面读取方法，这种加载称为“运行时加载”</p></li>
<li><p>编译时加载: ES6 模块不是对象，而是通过 export 命令显式指定输出的代码，输入时采用静态命令的形式。即在输入时可以指定加载某个输出值，而不是加载整个模块，这种加载称为“编译时加载”
注：上面提到 ES6 加载模块时是采用指定加载某个输出值的形式，如果你要想加载整个模块，你可以这么做：
<code>import * as customName from './moduleFileName';</code></p></li>
</ul>
</article>
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<a class="name" href="javascript:;">江矿叔叔.</a>
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