学习webpack4 - 基础配置
学习webpack4 - HTML处理
学习webpack4 - 样式处理
学习webpack4 - ES6语法转化
学习webpack4 - 第三方库的使用
学习webpack4 - 抽离公共代码

...持续中

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ES6语法转化

注意：开始之前以下内容之前，需要配置一些webpack的基础配置，传送门：学习webpack4.x - 基础配置

当前目录结构为：

• index.js 文件内容：

require('./index.css');
require('./index.scss');

• webpack.config.js文件内容：

let path = require('path');
let HtmlWebpackPlugin = require('html-webpack-plugin');
let MiniCssExtractPlugin = require('mini-css-extract-plugin'); //抽离CSS
let OptimizeCssPlugin = require('optimize-css-assets-webpack-plugin'); //优化项，比如压缩css等
let UglifyJsPlugin = require('uglifyjs-webpack-plugin'); //压缩jsmodule.exports = {// mode: 'development',//优化项配置optimization: {minimizer: [new OptimizeCssPlugin(),new UglifyJsPlugin({cache: true, //缓存parallel: true, //并发打包sourceMap: true //源码映射便于调试})]},//开一个本地服务devServer: {port: 3000, //端口号progress: true, //进度条contentBase: './dist', //指定目录运行服务open: true //自动打开浏览器},entry: './src/index.js',output: {filename: 'bundle.js',path: path.resolve(__dirname, 'dist')},// 模块配置module: {rules: [{test: /\.(css|scss)$/,use: [MiniCssExtractPlugin.loader, 'css-loader', 'postcss-loader', 'sass-loader']}]},//插件配置plugins: [new HtmlWebpackPlugin({template: './src/index.html', //原始文件filename: 'index.html', //打包后的文件名称hash: true, //hash}),new MiniCssExtractPlugin({filename: 'main.css' //抽离出的css文件名称})]
}

• package.json文件内容：

{"name": "webpack","version": "1.0.0","main": "index.js","license": "MIT","scripts": {"dev": "webpack --mode development && webpack-dev-server","build": "webpack --mode production"},"devDependencies": {"autoprefixer": "^9.4.7","css-loader": "^2.1.0","html-webpack-plugin": "^3.2.0","less": "^3.9.0","less-loader": "^4.1.0","mini-css-extract-plugin": "^0.5.0","node-sass": "^4.11.0","optimize-css-assets-webpack-plugin": "^5.0.1","postcss-loader": "^3.0.0","sass-loader": "^7.1.0","style-loader": "^0.23.1","uglifyjs-webpack-plugin": "^2.1.1","webpack": "^4.29.4","webpack-cli": "^3.2.3","webpack-dev-server": "^3.1.14","webpack-html-plugin": "^0.1.1"}
}

将ES6转化为ES5

step1: 打开src/index.js，输入：

const fn = () => {console.log('丸子');
}fn ();

step2: 配置webpack.config.js文件：

将ES6转成ES5，需要babel-loader，配置规则为：

module.exports = {//...module: {//...{test: /\.js$/,use: {loader: 'babel-loader',options: {presets: ['@babel/preset-env'] // 根据目标浏览器自动转换为相应es5代码}}}}
};

step3: 安装插件：

yarn add babel-loader @babel/core @babel/preset-env -D

尝试运行： npm run dev, 成功！如下图：