官方例子
还有相应的 imagemin-gifsicle imagemin-pngquant imagemin-svgo

$_> npm i -D img-loader imagemin-mozjpeg imagemin html-webpack-plugin mini-css-extract-plugin html-loader url-loader css-loader
// webpack.config.js
const path = require('path');
const HTMLWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
module.exports = {
    entry: {
        index: './app.js',
    },
    output: {
        path: path.resolve(__dirname, 'dist'),
        filename: '[name].bundle.js',
    },
    module: {
        rules: [
            {
                test: /\.html$/,
                use: 'html-loader'
            },
            {
                test: /\.css$/,
                use: [{ loader: MiniCssExtractPlugin.loader },
                { loader: 'css-loader' },
                ]

            },
            {
                test: /\.(png|jpg|jpef|gif|)$/,
                use: [{
                    loader:'url-loader',
                    options: {
                        limit: 20480, // 字节数，小于转base64
                        useRelativePath: true
                    },
                },
                    {
                        loader: 'img-loader',
                        options: {
                            plugins: [
                                require('imagemin-mozjpeg')({
                                    progressive: true,
                                    arithmetic: false
                                  }),
                            ]
                        }
                    }
            ]
            }
        ]
    },
    plugins: [
        new HTMLWebpackPlugin({
            title: 'css',
            template: './index.html',
            chunks: ['index']
        }),
        new MiniCssExtractPlugin({
            filename: "[name].css",
            chunkFilename: "[id].css"
        })
    ],
    mode: 'development'
};