webpack4.29.0基本用法

不积跬步无以至千里，不积小流无以成江海

# 准备工作 + 全局安装webpack和webpack-cli >sudo npm install webpack -g >sudo npm install webpack-cli -g

文件夹下局部安装

npm init -y
sudo npm install webpack –save-dev
sudo npm install webpack-cli –save-dev

实现对一个js文件打包

//webpack.config.js
const path = require('path')
module.exports = {
    mode:'development',
    entry:'./app.js',
    output:{
        filename:'[name].bundle.js',
        path:path.join(__dirname,'./dist'),
  }
}
这样就能在dist目录下出现一个app.bundle.js文件啦！

实现多个js文件打包

//webpack.config.js
const path = require('path')
const CleanWebpackPlugin = require('clean-webpack-plugin')
module.exports = {
    mode: 'development',
    entry: {
        index: './src/index.js',
        test: './src/test.js',
        test1: './src/test1.js',
    },
    output: {
        path: path.join(__dirname,'./dist/js'),
        filename:'[name]-[hash].js',
        pubicPath: 'http://cdn.con' //请求时会自己加协议（location.protocol='http'）和端口号(host='cdn.con')
    }，
    plugins: [
        new CleanWebpackPlugin (['./dist/js']) //清除之前打包的文件
    ]
}

使用模版实现每个js对应自己的html

//webpack.config.js
const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin') //模版loader
const CleanWebpackPlugin = require('clean-webpack-plugin')
module.exports = {
    entry:{
        index:'./src/index.js',
        test:'./src/test.js',
        test1:'./src/test1.js',
    },
    output:{
        path:path.join(__dirname,'./dist/js'),
        filename:'[name]-[hash].js',
        publicPath:"http://cdn.com"
    },
    plugins:[
        new HtmlWebpackPlugin({
            title: 'this a index.html', //每个html 的title
            template:'hello.html',
            filename:'index.html',
            excludeChunks:['test','test1'] //排除名为test.js,test1.js打包的js文件
        }),
        new HtmlWebpackPlugin({
            title:'this a test.js',
            template:'hello.html',
            filename:'test.html',
            excludeChunks:['index','test1']
        }),
        new HtmlWebpackPlugin({
            title:'this a test1.js',
            template:'hello.html',
            filename:'test1.html',
            excludeChunks:['test','index']       
        }),
        new CleanWebpackPlugin(['./dist/js'])
    ]
}

//hello.html 模版内容
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title><%= htmlWebpackPlugin.options.title%></title>
<script type="text/javascript">
    <%=
    compilation.assets[htmlWebpackPlugin.files.chunks.test1.entry.substr
    (htmlWebpackPlugin.files.publicPath.length)].source() %>
</script>
</head>
<body>
    <% for(let k in htmlWebpackPlugin.files.chunks) {%>
        <% if(k != 'index') {%>
            <script src="<%=htmlWebpackPlugin.files.chunks[k].entry %>"></script>
        <% }%>
    <% } %>
</body>

使用file-loader|css-loader|style-loader|postcss-loader

//webpack.config.js
module.exports = {
mode: 'development',
entry: './app.js',
output: {
    filename: '[name].bundle.js',
    path: path.join(__dirname, './dist/js1'),
},
plugins: [
    new CleanWebpackPlugin(['./dist/js1']),
    require('autoprefixer')
],
module: {
    rules: [
    {
        test: /\.(le|c)ss$/,
        test: /\.(png|jpg|gif)$/,
        use: [
        { loader: "style-loader" },
        { loader: "css-loader" },
        { loader: 'file-loader'},
        {
            loader: "postcss-loader",
            options: {
            plugins: [
                require("autoprefixer") /*在这里添加*/,
            ],
            }
        }
        ]

    }
    ]
 },
}

简单打包一个库的演示

//webapck.config.js
const path = require('path');

module.exports = {
    mode:'development',
    entry: './src/index.js',
    // 不打包进自己写的库的代码中，在业务代码中加载
    externals:['lodash'],
    output: {
        path: path.resolve(__dirname, 'dist'),
        // 文件打包后的文件名字
        filename: 'library.js',
        //可以使用src引入变为全局变量
        library:'library',   
        //以上library挂载的地方（比如this window等）
        libraryTarget: "umd"
    }
};