anchor.diff:    You'll need polyfills to run an Angular application in most browsers as explained
     in the [Browser Support](browser-support.html) guide.
   
  +  我们在[_浏览器支持_](browser-support.html)章节里解释过，Angular应用要能在大多数的浏览器里运行，它还需要一些polyfills。
  +
     Polyfills should be bundled separately from the application and vendor bundles.
     Add a `polyfills.ts` like this one to the `src/` folder.
  +
  +  Polyfills最好跟应用代码和vendor代码区分开来单独打包，所以我们需要在`src/`文件夹里添加一个`polyfills.ts`文件，代码如下：
   
   +makeExample('webpack/ts/src/polyfills.ts', '', 'src/polyfills.ts')(format=".")
   
  
positive.code:   :marked
      Load `zone.js` early within `polyfills.ts`, immediately after the other ES6 and metadata shims.
  
  :marked
    Because this bundle file will load first, `polyfills.ts` is also a good place to configure the browser environment
    for production or development.
  
  a(id="common-configuration")
  .l-main-section
  :marked
    ### Common configuration
  
    Developers typically have separate configurations for development, production, and test environments.
    All three have a lot of configuration in common.
  
    Gather the common configuration in a file called `webpack.common.js`.
  
  +makeExample('webpack/ts/config/webpack.common.js', null, 'config/webpack.common.js')(format=".")
  
  a#inside-webpack-commonjs
  :marked
    ### Inside _webpack.common.js_
    
    Webpack is a NodeJS-based tool that reads configuration from a JavaScript commonjs module file.
  
    The configuration imports dependencies with `require` statements
    and exports several objects as properties of a `module.exports` object.
  
    * [`entry`](#common-entries)&mdash;the entry-point files that define the bundles.
    * [`resolve`](#common-resolve)&mdash;how to resolve file names when they lack extensions.
    * [`module.rules`](#common-rules)&mdash; `module` is an object with `rules` for deciding how files are loaded.
    * [`plugins`](#common-plugins)&mdash;creates instances of the plugins.
  
  a#common-entries
  :marked
    #### _entry_
  
    The first export is the `entry` object:
  
  +makeExample('webpack/ts/config/webpack.common.js', 'entries', 'config/webpack.common.js')(format=".")
  
  :marked
    This `entry` object defines the three bundles:
  
    * `polyfills`&mdash;the polyfills needed to run Angular applications in most modern browsers.
    * `vendor`&mdash;the third-party dependencies such as Angular, lodash, and bootstrap.css.
    * `app`&mdash;the application code.
  
  a#common-resolve
  :marked
    #### _resolve_ extension-less imports
  
    The app will `import` dozens if not hundreds of JavaScript and TypeScript files.
    You could write `import` statements with explicit extensions like this example:
  
  .code-example
    code-example(language="typescript").
  
negative.code:   After that brief orientation, you are ready to build your own Webpack configuration for Angular apps. 
    
    经过简短的培训之后，我们准备为Angular应用构建一份自己的Webpack配置了。
  
    Begin by setting up the development environment.
    
    从设置开发环境开始。
  