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- 2-7 其它配置项
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- 2-8 整体配置结构
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- 2-9 多种配置类型
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- 3-1 使用 ES6 语言
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- 3-2 使用 TypeScript 语言
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- 3-3 使用 Flow 检查器
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- 3-6 使用 React 框架
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- 3-7 使用 Vue 框架
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- 3-8 使用 Angular2 框架
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- 3-9 为单页应用生成 HTML
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- 3-10 管理多个单页应用
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- 3-11 构建同构应用
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- 3-12 构建 Electron 应用
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- 3-13 构建 Npm 模块
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- 3-14 构建离线应用
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- 3-15 搭配 Npm Script
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- 3-16 检查代码
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- 3-17 通过 Node.js API 启动 Webpack
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- 3-18 使用 Webpack Dev Middleware
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- 3-19 加载图片
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- 3-20 加载SVG
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- 3-21 加载 Source Map
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- 3-22 实战总结
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- 第4章 优化
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- 4-1 缩小文件搜索范围
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- 4-2 使用 DllPlugin
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- 4-3 使用 HappyPack
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- 4-4 使用 ParallelUglifyPlugin
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- 4-5 使用自动刷新
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- 4-6 开启模块热替换
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- 4-7 区分环境
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- 4-8 压缩代码
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- 4-9 CDN 加速
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- <h1 id="3-18-使用-webpack-dev-middleware">3-18 使用 Webpack Dev Middleware</h1>
- <p>在 <a href="../1入门/1-6使用DevServer.html">1-6 使用 DevServer</a> 中介绍过的 DevServer 是一个方便开发的小型 HTTP 服务器,
- DevServer 其实是基于 <a href="https://github.com/webpack/webpack-dev-middleware" target="_blank">webpack-dev-middleware</a> 和 <a href="https://expressjs.com" target="_blank">Expressjs</a> 实现的,
- 而 webpack-dev-middleware 其实是 Expressjs 的一个中间件。</p>
- <p>也就是说,实现 DevServer 基本功能的代码大致如下:</p>
- <pre><code class="lang-js"><span class="hljs-keyword">const</span> express = <span class="hljs-built_in">require</span>(<span class="hljs-string">'express'</span>);
- <span class="hljs-keyword">const</span> webpack = <span class="hljs-built_in">require</span>(<span class="hljs-string">'webpack'</span>);
- <span class="hljs-keyword">const</span> webpackMiddleware = <span class="hljs-built_in">require</span>(<span class="hljs-string">'webpack-dev-middleware'</span>);
- <span class="hljs-comment">// 从 webpack.config.js 文件中读取 Webpack 配置 </span>
- <span class="hljs-keyword">const</span> config = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./webpack.config.js'</span>);
- <span class="hljs-comment">// 实例化一个 Expressjs app</span>
- <span class="hljs-keyword">const</span> app = express();
- <span class="hljs-comment">// 用读取到的 Webpack 配置实例化一个 Compiler</span>
- <span class="hljs-keyword">const</span> compiler = webpack(config);
- <span class="hljs-comment">// 给 app 注册 webpackMiddleware 中间件</span>
- app.use(webpackMiddleware(compiler));
- <span class="hljs-comment">// 启动 HTTP 服务器,服务器监听在 3000 端口 </span>
- app.listen(<span class="hljs-number">3000</span>);
- </code></pre>
- <p>从以上代码可以看出,从 <code>webpack-dev-middleware</code> 中导出的 <code>webpackMiddleware</code> 是一个函数,该函数需要接收一个 Compiler 实例。
- 在 <a href="3-17通过Node.jsAPI启动Webpack.html">3-17 通过 Node.js API 启动 Webpack</a> 中曾介绍过 Webpack API 导出的 <code>webpack</code> 函数会返回一个Compiler 实例。</p>
- <p><code>webpackMiddleware</code> 函数的返回结果是一个 Expressjs 的中间件,该中间件有以下功能:</p>
- <ul>
- <li>接收来自 Webpack Compiler 实例输出的文件,但不会把文件输出到硬盘,而是保存在内存中;</li>
- <li>往 Expressjs app 上注册路由,拦截 HTTP 收到的请求,根据请求路径响应对应的文件内容;</li>
- </ul>
- <p>通过 webpack-dev-middleware 能够将 DevServer 集成到你现有的 HTTP 服务器中,让你现有的 HTTP 服务器能返回 Webpack 构建出的内容,而不是在开发时启动多个 HTTP 服务器。
- 这特别适用于后端接口服务采用 Node.js 编写的项目。 </p>
- <h2 id="webpack-dev-middleware-支持的配置项">Webpack Dev Middleware 支持的配置项</h2>
- <p>在 Node.js 中调用 webpack-dev-middleware 提供的 API 时,还可以给它传入一些配置项,方法如下:</p>
- <pre><code class="lang-js"><span class="hljs-comment">// webpackMiddleware 函数的第二个参数为配置项</span>
- app.use(webpackMiddleware(compiler, {
- <span class="hljs-comment">// webpack-dev-middleware 所有支持的配置项</span>
- <span class="hljs-comment">// 只有 publicPath 属性为必填,其它都是选填项</span>
- <span class="hljs-comment">// Webpack 输出资源绑定在 HTTP 服务器上的根目录,</span>
- <span class="hljs-comment">// 和 Webpack 配置中的 publicPath 含义一致 </span>
- publicPath: <span class="hljs-string">'/assets/'</span>,
- <span class="hljs-comment">// 不输出 info 类型的日志到控制台,只输出 warn 和 error 类型的日志</span>
- noInfo: <span class="hljs-literal">false</span>,
- <span class="hljs-comment">// 不输出任何类型的日志到控制台</span>
- quiet: <span class="hljs-literal">false</span>,
- <span class="hljs-comment">// 切换到懒惰模式,这意味着不监听文件变化,只会在请求到时再去编译对应的文件,</span>
- <span class="hljs-comment">// 这适合页面非常多的项目。</span>
- lazy: <span class="hljs-literal">true</span>,
- <span class="hljs-comment">// watchOptions</span>
- <span class="hljs-comment">// 只在非懒惰模式下才有效</span>
- watchOptions: {
- aggregateTimeout: <span class="hljs-number">300</span>,
- poll: <span class="hljs-literal">true</span>
- },
- <span class="hljs-comment">// 默认的 URL 路径, 默认是 'index.html'.</span>
- index: <span class="hljs-string">'index.html'</span>,
- <span class="hljs-comment">// 自定义 HTTP 头</span>
- headers: {<span class="hljs-string">'X-Custom-Header'</span>: <span class="hljs-string">'yes'</span>},
- <span class="hljs-comment">// 给特定文件后缀的文件添加 HTTP mimeTypes ,作为文件类型映射表</span>
- mimeTypes: {<span class="hljs-string">'text/html'</span>: [<span class="hljs-string">'phtml'</span>]},
- <span class="hljs-comment">// 统计信息输出样式</span>
- stats: {
- colors: <span class="hljs-literal">true</span>
- },
- <span class="hljs-comment">// 自定义输出日志的展示方法</span>
- reporter: <span class="hljs-literal">null</span>,
- <span class="hljs-comment">// 开启或关闭服务端渲染</span>
- serverSideRender: <span class="hljs-literal">false</span>,
- }));
- </code></pre>
- <h2 id="webpack-dev-middleware-与模块热替换">Webpack Dev Middleware 与模块热替换</h2>
- <p>DevServer 提供了一个方便的功能,可以做到在监听到文件发生变化时自动替换网页中的老模块,以做到实时预览。
- DevServer 虽然是基于 webpack-dev-middleware 实现的,但 webpack-dev-middleware 并没有实现模块热替换功能,而是 DevServer 自己实现了该功能。</p>
- <p>为了在使用 webpack-dev-middleware 时也能使用模块热替换功能去提升开发效率,需要额外的再接入 <a href="https://github.com/glenjamin/webpack-hot-middleware" target="_blank">webpack-hot-middleware</a>。
- 需要做以下修改才能实现模块热替换。</p>
- <p>第2步:修改 <code>webpack.config.js</code> 文件,加入 <code>HotModuleReplacementPlugin</code> 插件,修改如下:</p>
- <pre><code class="lang-js"><span class="hljs-keyword">const</span> HotModuleReplacementPlugin = <span class="hljs-built_in">require</span>(<span class="hljs-string">'webpack/lib/HotModuleReplacementPlugin'</span>);
- <span class="hljs-built_in">module</span>.exports = {
- entry: [
- <span class="hljs-comment">// 为了支持模块热替换,注入代理客户端</span>
- <span class="hljs-string">'webpack-hot-middleware/client'</span>,
- <span class="hljs-comment">// JS 执行入口文件</span>
- <span class="hljs-string">'./src/main.js'</span>
- ],
- output: {
- <span class="hljs-comment">// 把所有依赖的模块合并输出到一个 bundle.js 文件</span>
- filename: <span class="hljs-string">'bundle.js'</span>,
- },
- plugins: [
- <span class="hljs-comment">// 为了支持模块热替换,生成 .hot-update.json 文件</span>
- <span class="hljs-keyword">new</span> HotModuleReplacementPlugin(),
- ],
- devtool: <span class="hljs-string">'source-map'</span>,
- };
- </code></pre>
- <p>该修改其实就是相当于完成了在 <a href="../4优化/4-6开启模块热替换.html">4-6 开启模块热替换</a> 中提到的 <code>webpack-dev-server --hot</code> 的工作。</p>
- <p>第1步:修改 HTTP 服务器代码 <code>server.js</code> 文件,接入 <code>webpack-hot-middleware</code> 中间件,修改如下:</p>
- <pre><code class="lang-js"><span class="hljs-keyword">const</span> express = <span class="hljs-built_in">require</span>(<span class="hljs-string">'express'</span>);
- <span class="hljs-keyword">const</span> webpack = <span class="hljs-built_in">require</span>(<span class="hljs-string">'webpack'</span>);
- <span class="hljs-keyword">const</span> webpackMiddleware = <span class="hljs-built_in">require</span>(<span class="hljs-string">'webpack-dev-middleware'</span>);
- <span class="hljs-comment">// 从 webpack.config.js 文件中读取 Webpack 配置</span>
- <span class="hljs-keyword">const</span> config = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./webpack.config.js'</span>);
- <span class="hljs-comment">// 实例化一个 Expressjs app</span>
- <span class="hljs-keyword">const</span> app = express();
- <span class="hljs-comment">// 用读取到的 Webpack 配置实例化一个 Compiler</span>
- <span class="hljs-keyword">const</span> compiler = webpack(config);
- <span class="hljs-comment">// 给 app 注册 webpackMiddleware 中间件</span>
- app.use(webpackMiddleware(compiler));
- <span class="hljs-comment">// 为了支持模块热替换,响应用于替换老模块的资源</span>
- app.use(<span class="hljs-built_in">require</span>(<span class="hljs-string">'webpack-hot-middleware'</span>)(compiler));
- <span class="hljs-comment">// 把项目根目录作为静态资源目录,用于服务 HTML 文件</span>
- app.use(express.static(<span class="hljs-string">'.'</span>));
- <span class="hljs-comment">// 启动 HTTP 服务器,服务器监听在 3000 端口</span>
- app.listen(<span class="hljs-number">3000</span>, () => {
- <span class="hljs-built_in">console</span>.info(<span class="hljs-string">'成功监听在 3000'</span>);
- });
- </code></pre>
- <p>第3步:修改执行入口文件 <code>main.js</code>,加入替换逻辑,在文件末尾加入以下代码:</p>
- <pre><code class="lang-js"><span class="hljs-keyword">if</span> (<span class="hljs-built_in">module</span>.hot) {
- <span class="hljs-built_in">module</span>.hot.accept();
- }
- </code></pre>
- <p>第4步:安装新引入的依赖:</p>
- <pre><code class="lang-bash">npm i -D webpack-dev-middleware webpack-hot-middleware express
- </code></pre>
- <p>安装成功后,通过 <code>node ./server.js</code> 就能启动一个类似于 DevServer 那样支持模块热替换的自定义 HTTP 服务了。</p>
- <blockquote>
- <p>本实例<a href="http://webpack.wuhaolin.cn/3-18使用WebpackDevMiddleware.zip" target="_blank">提供项目完整代码</a></p>
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