指导小伙伴在webstorm+nodejs环境下新建项目时，小伙伴出现了一个很神奇的问题：没有执行webpack-dev-server情况下，即使执行npm init，也不会出现package.json文件。原本的印象中package.json是保存文件基本信息以及依赖包版本的文件。不知道为什么他和webpack-dev-server有关系。就开始研究webpack-dev-server的相关概念等。
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.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<script src="assets/bundle.js"></script>
</body>
</html>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:8080/webpack...
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
<script src="http://localhost:8080/webpack-dev-server.js"></script>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/webpack-dev-server/pull/127 ).
proxy: {
"**": "http://localhost:9090"
},
setup: function(app) {
// Here you can access the Express app object and add your own custom 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();
webpack和webpack-dev-server的区别
参考:http://webpack.github.io/docs...
webstorm相关nodejs配置参考：http://www.cnblogs.com/xxx91hx/p/7055582.html
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2017-8-24添加：小伙伴出现的webpack-dev-server和package.json的问题是弄混了。package,json文件是需要在npm init之后，一直点击回车输入要填写进package.json的内容，因为小伙伴不了解，没有点击回车时就以为结束了。webpack-dev-server是启用服务器，具体的研究还是参照上方。