webpack.config.js ：

const webpack = require("webpack");

module.exports = {
  entry: {
    "bundle": "./entry.js",
    "bundle.min": "./entry.js",
  },
  devtool: "source-map",
  output: {
    path: "./dist",
    filename: "[name].js"
  },
  plugins: [
    new webpack.optimize.UglifyJsPlugin({
      include: /\.min\.js$/,
      minimize: true
    })
  ]
};

自 Webpack 4 以来，webpack.optimize.UglifyJsPlugin已弃用，并且使用它会导致错误：

webpack.optimize.UglifyJsPlugin 已被移除，请改用 config.optimization.minimize

正如手册所解释的，插件可以替换为minimize选项。可以通过指定UglifyJsPlugin实例向插件提供自定义配置：

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

module.exports = {
  // ...
  optimization: {
    minimize: true,
    minimizer: [new UglifyJsPlugin({
      include: /\.min\.js$/
    })]
  }
};

这完成了简单设置的工作。更有效的解决方案是将 Gulp 与 Webpack 一起使用，并一次性完成相同的操作。