js: webpack插件的使用

js: webpack插件的使用

webpack中文文档： https://webpack.docschina.org/concepts/

执行webpack

$ npx webpack

一、js压缩插件UglifyJsPlugin

https://www.npmjs.com/package/uglifyjs-webpack-plugin

依赖 package.json

{
  "devDependencies": {
    "uglifyjs-webpack-plugin": "^2.2.0",
    "webpack": "^5.31.2",
    "webpack-cli": "^4.6.0"
  }
}

用于测试的js

./src/index.js

// 输出字符串
function hello() {
  console.log("hello");
}

hello();

// 加法运算
function addNumber(a, b) {
  return a + b;
}

console.log(addNumber(1, 2));
console.log(addNumber(1, 3));

1、直接输出js

./dist/main.js

(()=>{function o(o,l){return o+l}console.log("hello"),console.log(o(1,2)),console.log(o(1,3))})();

2、使用插件UglifyJsPlugin 对 js文件进行压缩

webpack.config.js

const UglifyJsPlugin = require("uglifyjs-webpack-plugin");

module.exports = {
  // 默认值
  // entry: './src/index.js',
  // output: './dist/main.js',

  optimization: {
    minimizer: [new UglifyJsPlugin()],
  },

  mode: "production", // 'development' or 'production'
};

输出结果：

./dist/main.js

console.log("hello"),console.log(3),console.log(4);

二、css提取插件：MiniCssExtractPlugin

https://www.npmjs.com/package/mini-css-extract-plugin

依赖 package.json

{
  "devDependencies": {
    "css-loader": "^5.2.1",
    "mini-css-extract-plugin": "^1.4.1",
    "webpack": "^5.31.2",
    "webpack-cli": "^4.6.0"
  }
}

./src/style-1.css

body {
  background: blue;
}

./src/style-2.css

body {
  background: green;
}

./src/index.js

import './style-1.css';
import './style-2.css';

webpack默认不处理css文件，使用css-loader处理

webpack.config.js

module.exports = {
  // 默认值
  // entry: './src/index.js',
  // output: './dist/main.js',

  module: {
    rules: [
      {
        test: /\.css$/i,
        use: ["css-loader"],
      },
    ],
  },

  mode: "production", // 'development' or 'production'
};

输出如下

(() => {
  "use strict";
  var n = {
      634: (n, r, t) => {
        var o = t(587);
        t.n(o)()(function (n) {
          return n[1];
        }).push([n.id, "body {\n  background: blue;\n}\n", ""]);
      },
      358: (n, r, t) => {
        var o = t(587);
        t.n(o)()(function (n) {
          return n[1];
        }).push([n.id, "body {\n  background: green;\n}\n", ""]);
      },
      587: (n) => {
        n.exports = function (n) {
          var r = [];
          return (
            (r.toString = function () {
              return this.map(function (r) {
                var t = n(r);
                return r[2] ? "@media ".concat(r[2], " {").concat(t, "}") : t;
              }).join("");
            }),
            (r.i = function (n, t, o) {
              "string" == typeof n && (n = [[null, n, ""]]);
              var e = {};
              if (o)
                for (var a = 0; a  n.default : () => n;
    return t.d(r, { a: r }), r;
  }),
    (t.d = (n, r) => {
      for (var o in r)
        t.o(r, o) &&
          !t.o(n, o) &&
          Object.defineProperty(n, o, { enumerable: !0, get: r[o] });
    }),
    (t.o = (n, r) => Object.prototype.hasOwnProperty.call(n, r)),
    t(634),
    t(358);
})();

使用插件 MiniCssExtractPlugin 将css单独抽离出来

const MiniCssExtractPlugin = require("mini-css-extract-plugin");

module.exports = {
  // 默认值
  // entry: './src/index.js',
  // output: './dist/main.js',

  plugins: [new MiniCssExtractPlugin()],

  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [MiniCssExtractPlugin.loader, "css-loader"],
      },
    ],
  },

  mode: "production", // 'development' or 'production'
};

输出了一个新的css文件

./dist/main.css

body {
  background: blue;
}

body {
  background: green;
}

三、 生成html插件 HtmlWebpackPlugin

https://www.npmjs.com/package/html-webpack-plugin

依赖 package.json

{
  "devDependencies": {
    "html-webpack-plugin": "^5.3.1",
    "webpack": "^5.31.2",
    "webpack-cli": "^4.6.0"
  }
}

webpack.config.js

const HtmlWebpackPlugin = require('html-webpack-plugin')

module.exports = {
  plugins: [
    new HtmlWebpackPlugin()
  ]
}

四、使用开发服务器 devServer

依赖 package.json

{
  "devDependencies": {
    "webpack": "^5.31.2",
    "webpack-cli": "^4.6.0",
    "webpack-dev-server": "^3.11.2"
  }
}

实现自动热更新

const path = require('path');

module.exports = {
  // 默认值
  // entry: './src/index.js',
  // output: './dist/main.js',

  devServer: {
    contentBase: path.join(__dirname, 'dist'),
    port: 9000,
    hot: true,
    open: true,
  },

  mode: "development", // 'development' or 'production'
};

启动

$ npx webpack serve