详解webpack

详解webpack

webpack-dev-server

webpack-dev-server是一个小型的Node.js Express服务器,它使用webpack-dev-middleware来服务于webpack的包,除此自外，它还有一个通过Sock.js来连接到服务器的微型运行时.

我们来看一下下面的配置文件(webpack.config.js)

var path = require("path");

module.exports = {

entry:{

app:["./app/main.js"]

},

output:{

path:path.resolve(__dirname,"build"),

publicPath:"/assets/",

filename:"bundle.js"

}

}

这里你将你的源文件放在app文件夹下,并通过webpack将其打包到build文件夹下的bundle.js中.

注意:webpack-dev-server是一个独立的NPM包,你可以通过npm install webpack-dev-server来安装它.

基本目录

webpack-dev-server默认会以当前目录为基本目录,除非你制定它.

webpack-dev-server --content-base build/

上述命令是在命令行中执行的,它将build目录作为根目录.有一点需要注意的是:webpack-dev-server生成的包并没有放在你的真实目录中,而是放在了内存中.

我们在基本目录下新建一个index.html文件,然后在浏览器中输入http://localhost:8080访问.

自动刷新

webpack-dev-server支持两种模式来自动刷新页面.

iframe模式(页面放在iframe中,当发生改变时重载)

inline模式(将webpack-dev-sever的客户端入口添加到包(bundle)中)

两种模式都支持热模块替换(Hot Module Replacement).热模块替换的好处是只替换更新的部分,而不是页面重载.

iframe模式

使用这种模式不需要额外的配置,只需要以下面这种URL格式访问即可

http://«host»:«port»/webpack-dev-server/«path»

例如:http://localhost:ncPSpp8080/webpack-dev-server/index.html.

inline模式

inline模式下我们访问的URL不用发生变化,启用这种模式分两种情况:

1 当以命令行启动webpack-dev-server时,需要做两点：

在命令行中添加--inline命令

在webpack.config.js中添加devServer:{inline:true}

2 当以Node.js API启动webpack-dev-server时,我们也需要做两点:

由于webpack-dev-server的配置中无inline选项,我们需要添加webpack-dev-server/client?http://«path»:«port»/到webpack配置的entry入口点中.

将添加到html文件中

var config = require("./webpack.config.js");

var webpack = require('webpack');

var WebpackDevServer = require('webpack-dev-server');

config.entry.app.unshift("webpack-dev-server/client?http://localhost:8080/");

var compiler = webpack(config);

var server = new WebpackDevServer(compiler, {

contentBase:'build/',

publicPath: "/assets/"

});

server.listen(8080);

在Node中运行上面的代码即可。

注意：webpack配置中的devSever配置项只对在命令行模式有效。

(Hot Module Replacement)热模块替换

在命令行中运行inline模式，并启用热模块替换

这里只需要多增加 --hot指令就OK了.如下所示.

webpack-dev-server --content-base build --inline --hot

注意:命令行模式下,webpack.config.js中一定要配置output.publicPath来指定编译后的包(bundle)的访问位置.

在Nodejs API中运行inline模式，并启用热模块替换

这里需要做以下三点:

在webpack.config.js的entry选项中添加:webpack/hot/dev-server

在webpack.config.js的plugins选项中添加:new webpack.HotModuleReplacementPlugin()

在webpack-dev-server的配置中添加：hot:true

webpack-dev-server中的配置选项

var WebpackDevServer = require("webpack-dev-server");

var webpack = require("webpack");

var compiler = webpack({

// configuration

});

var server = new WebpackDevServer(compiler, {

// webpack-dev-server options

contentBase: "/path/to/directory",

// Can also be an array, or: contentBase: "http://localhost/",

hot: true,

// Enable special support for Hot Module Replacement

// Page is no longer updated, but a "webpackHotUpdate" message is send to the content

// Use "webpack/hot/dev-server" as additional module in your entry point

// Note: this does _not_ add the `HotModuleReplacementPlugin` like the CLI option does.

// Set this as true if you want to access dev server from arbitrary url.

// This is handy if you are using a html5 router.

historyApiFallback: false,

// Set this if you want to enable gzip compression for assets

compress: true,

// Set this if you want webpack-dev-server to delegate a single path to an arbitrary server.

// Use "**" to proxy all paths to the specified server.

// This is useful if you want to get rid of 'http://localhost:8080/' in script[src],

// and has many other use cases (see https://github.com/webpack/wncPSppebpack-dev-server/pull/127 ).

proxy: {

"**": "http://localhost:9090"

},

setup: function(app) {

// Here you can access the Express app object and add your own chttp://ustom middleware to it.

// For example, to define custom handlers for some paths:

// app.get('/some/path', function(req, res) {

// res.json({ custom: 'response' });

// });

},

// pass [static options](http://expressjs.com/en/4x/api.html#express.static) to inner express server

staticOptions: {

},

// webpack-dev-middleware options

quiet: false,

noInfo: false,

lazy: true,

filename: "bundle.js",

watchOptions: {

aggregateTimeout: 300,

poll: 1000

},

// It's a required option.

publicPath: "/assets/",

headers: { "X-Custom-Header": "yes" },

stats: { colors: true }

});

server.listen(8080, "localhost", function() {});

// server.close();

参考:http://webpack.github.io/docs/webpack-dev-server.html

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