接触webpack是好久之前的事情了，最近看了下webpack没想到都到4了。
webpack 是一个现代 JavaScript 应用程序的静态模块打包器(module bundler).
会创建1个依赖关系图(dependency graph),包含所有依赖的模块，然后将模块打包成1个或多个bundle.
webpack4 仍然支持高度可配，但完全可以不用配置文件了(基于mode)。
核心配置：
- 入口(entry)：
- 输出(output)：
- loader：
- 插件(plugins)：
基本特性
Entry
入口起点(entry point)指示 webpack 应该使用哪个模块，来作为构建其内部依赖图的开始。
可以通过在 webpack 配置中配置 entry 属性，来指定一个入口起点（或多个入口起点）。默认值为 ./src/index.js
webpack.config.js
module.exports = { ???entry: { ???????main: './src/index.js' ???},};Output
output 属性告诉 webpack 在哪里输出它所创建的 bundles，以及如何命名这些文件，默认值为./dist/[name].js
webpack.config.js
const path = require('path');module.exports = { ?entry: './src/index.js', ?output: { ???path: path.resolve(__dirname, 'dist'), ???filename: '[name].js' ?}};Loader
loader 让 webpack 能够去处理那些非 JavaScript 文件（webpack 自身只理解 JavaScript）。
loaders 有2个核心参数：
- test 属性，用于标识出需要转换的某个或某些文件。
- use 属性，表示进行转换时，应该使用哪个 loader。
const path = require('path');const config = { ?output: { ???filename: 'bundle.js' ?}, ?module: { ???rules: [ ?????{ test: /\.txt$/, use: 'raw-loader' } ???] ?}};module.exports = config;Plugins
插件的范围包括，从打包优化和压缩，一直到重新定义环境中的变量。插件接口功能极其强大，可以用来处理各种各样的任务。
webpack.config.js
const HtmlWebpackPlugin = require('html-webpack-plugin'); // 通过 npm 安装const webpack = require('webpack'); // 用于访问内置插件const config = { ?module: { ???rules: [ ?????{ test: /\.txt$/, use: 'raw-loader' } ???] ?}, ?plugins: [ ???new webpack.optimize.UglifyJsPlugin(), ???new HtmlWebpackPlugin({template: './src/index.html'}) ?]};module.exports = config;Mode
通过选择 development 或 production 之中的一个，来设置 mode 参数
webpack.config.js
module.exports = { ?mode: 'production'};mode.js
// webpack.development.config.jsmodule.exports = {+ mode: 'development'- plugins: [- ??new webpack.NamedModulesPlugin(),- ??new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("development") }),- ]}// webpack.production.config.jsmodule.exports = {+ ?mode: 'production',- ?plugins: [- ???new UglifyJsPlugin(/* ... */),- ???new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("production") }),- ???new webpack.optimize.ModuleConcatenationPlugin(),- ???new webpack.NoEmitOnErrorsPlugin()- ?]}常用插件
HtmlWebpackPlugin:
Options
const HtmlWebpackPlugin = require('html-webpack-plugin');new HtmlWebpackPlugin({ template: 'src/index.html', minify: true, hash: true })CleanWebpackPlugin:
const CleanWebpackPlugin = require('clean-webpack-plugin');new CleanWebpackPlugin(['dist'])MiniCssExtractPlugin(ExtractTextPlugin)：
new MiniCssExtractPlugin({ filename: "[name].css",chunkFilename: "[id].css" })module: { ???rules: [{ ???????test: /\.css$/, ???????use: [ ???????????MiniCssExtractPlugin.loader, ???????????'css-loader' ???????]} ???]}SplitChunksPlugin:
module.exports = { ???mode: 'development', ???entry: { ???????main: './src/index.js', ???????vendors: 'lodash' ???}, ???optimization: { ???????splitChunks: { ???????????cacheGroups: { ???????????????vendors: { ???????????????????test: /[\\/]node_modules[\\/]/, ???????????????????name: "vendors", ???????????????????chunks: "initial" ???????????????} ???????????} ???????} ???}}配置示例
const CleanWebpackPlugin = require('clean-webpack-plugin');const HtmlWebpackPlugin = require('html-webpack-plugin');const MiniCssExtractPlugin = require("mini-css-extract-plugin");const path = require('path');module.exports = { ???mode: 'development', ???entry: { ???????main: './src/index.js', ???}, ???devtool: 'inline-source-map', ???devServer: { ???????contentBase: './dist' ???}, ???output: { ???????path: path.resolve(__dirname, 'dist'), ???????filename: '[name].js', ???}, ???module: { ???????rules: [{ ???????????test: /\.css$/, ???????????use: [ ???????????????MiniCssExtractPlugin.loader, ???????????????'css-loader' ???????????] ???????}, { ???????????test: /\.(js|jsx)$/, ???????????loader: 'babel-loader', ???????????options: { ???????????????presets: ['react'] ???????????}, ???????????exclude: /node_modules/ ???????}] ???}, ???plugins: [ ???????new CleanWebpackPlugin(['dist']), ???????new HtmlWebpackPlugin({ template: 'src/index.html', minify: true, hash: true }), ???????new MiniCssExtractPlugin({ filename: "[name].css", chunkFilename: "[id].css" }) ???], ???externals: { ???????lodash: '_', ???????react: 'React', ???????'react-dom': 'ReactDOM' ???}, ???optimization: { ???????splitChunks: { ???????????cacheGroups: { ???????????????common: { ???????????????????test: /[\\/]node_modules[\\/]/, ???????????????????name: "common", ???????????????????chunks: "initial" ???????????????} ???????????} ???????} ???}};React从入门到放弃之前奏(1)：webpack4简介
原文地址：https://www.cnblogs.com/neverc/p/9044864.html