【前端必会】HtmlWebpackPlugin 和 SplitChunksPlugin 是什么?

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所属分类:Web前端
摘要

了解什么是webpack插件,在来看一下不能不知道的两个插件写2个按钮,点击分别加载页面1,页面2


背景

了解什么是webpack插件,在来看一下不能不知道的两个插件

  1. HtmlWebpackPlugin 有了这个插件,webpack执行后会自动帮我们在dist目录生成一个html文件,并且添加bundle.js的引用。
    https://webpack.docschina.org/plugins/html-webpack-plugin
  2. SplitChunksPlugin 这个插件可以协助我们在生成的bundle上进行更为精确的配置,比如node_modules下的模块单独打包到一个文件(方便缓存)等

开始

写2个按钮,点击分别加载页面1,页面2

//index.html <!DOCTYPE html> <html>   <head>     <meta charset="utf-8" />     <title>Webpack App</title>     <meta name="viewport" content="width=device-width,initial-scale=1" />   </head>   <body>     <h1>Hello webpack splitchunks</h1>     <button id="btn1">页面1</button>     <button id="btn2">页面2</button>   </body> </html>  
//入口脚本 window.addEventListener("load", function () {   var btn1 = document.getElementById("btn1");   btn1.addEventListener("click", function () {     import("./p1");   });    var btn2 = document.getElementById("btn2");   btn2.addEventListener("click", function () {     import("./p2");   }); }); 

两个页面

//页面1 import { max } from "lodash"; console.log("p1 lodash", max); 
//页面2 import { max } from "lodash"; console.log("p2 lodash", max); 
//webpack 配置 const webpack = require("webpack"); const HtmlWebpackPlugin = require("html-webpack-plugin"); const path = require("path"); const config = {   context: path.resolve(__dirname),   mode: "production",   optimization: {     minimize: false,   },   entry: "./main.js",   target: ["web", "es5"],   output: {     clean: true,     filename: "bundle.js",     path: path.resolve(__dirname, "dist"),   },   plugins: [     new HtmlWebpackPlugin({       template: "index.html",     }),   ], };  const compiler = webpack(config); compiler.run((err, stats) => {   console.log(err); });  

生成后的目录
【前端必会】HtmlWebpackPlugin 和 SplitChunksPlugin 是什么?

//bundle.js 关键代码 var __webpack_exports__ = {}; console.log("hello"); window.addEventListener("load", function () {   var btn1 = document.getElementById("btn1");   btn1.addEventListener("click", function () {     Promise.all(/* import() */[__webpack_require__.e(891), __webpack_require__.e(751)]).then(__webpack_require__.bind(__webpack_require__, 751));   });    var btn2 = document.getElementById("btn2");   btn2.addEventListener("click", function () {     Promise.all(/* import() */[__webpack_require__.e(891), __webpack_require__.e(291)]).then(__webpack_require__.bind(__webpack_require__, 291));   }); }); 
//751.bundle.js 关键代码 "use strict"; (self["webpackChunk"] = self["webpackChunk"] || []).push([[751],{  /***/ 751: /***/ (function(__unused_webpack_module, __webpack_exports__, __webpack_require__) {  __webpack_require__.r(__webpack_exports__); /* harmony import */ var lodash__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(891); /* harmony import */ var lodash__WEBPACK_IMPORTED_MODULE_0___default = /*#__PURE__*/__webpack_require__.n(lodash__WEBPACK_IMPORTED_MODULE_0__);  console.log("p1 lodash", lodash__WEBPACK_IMPORTED_MODULE_0__.max);  /***/ })  }]); 
//291.bundle.js 关键代码 "use strict"; (self["webpackChunk"] = self["webpackChunk"] || []).push([[291],{  /***/ 291: /***/ (function(__unused_webpack_module, __webpack_exports__, __webpack_require__) {  __webpack_require__.r(__webpack_exports__); /* harmony import */ var lodash__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(891); /* harmony import */ var lodash__WEBPACK_IMPORTED_MODULE_0___default = /*#__PURE__*/__webpack_require__.n(lodash__WEBPACK_IMPORTED_MODULE_0__);  console.log("p2 lodash", lodash__WEBPACK_IMPORTED_MODULE_0__.max);  /***/ })  }]); 
//891.bundle.js 关键代码(lodash模块代码) (self["webpackChunk"] = self["webpackChunk"] || []).push([[891],{  /***/ 891: /***/ (function(module, exports, __webpack_require__) {  /* module decorator */ module = __webpack_require__.nmd(module); var __WEBPACK_AMD_DEFINE_RESULT__;/**  * @license  * Lodash <https://lodash.com/>  * Copyright OpenJS Foundation and other contributors <https://openjsf.org/>  * Released under MIT license <https://lodash.com/license>  * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>  * Copyright Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors  */ ;(function() {    /** Used as a safe reference for `undefined` in pre-ES5 environments. */   var undefined;    /** Used as the semantic version number. */   var VERSION = '4.17.21';    /** Used as the size to enable large array optimizations. */   var LARGE_ARRAY_SIZE = 200; ...... 

总结

  1. 使用了异步加载模块,自动生成2个bundle(751、251)。异步模块好像一定是会拆分为一个新的文件(不确定)
  2. 2个模块都引用了lodash,所以lodash又单独拆出一个bundle(891)
  3. 进入页面加载
    【前端必会】HtmlWebpackPlugin 和 SplitChunksPlugin 是什么?
  4. 点击按钮1
    【前端必会】HtmlWebpackPlugin 和 SplitChunksPlugin 是什么?
  5. 点击按钮2
    【前端必会】HtmlWebpackPlugin 和 SplitChunksPlugin 是什么?
  6. 多看文档、多看文档、多看文档
    https://webpack.docschina.org/plugins/split-chunks-plugin/