webpack4--提取css到单独文件并且压缩css

提取css到build/css目录下：mini-css-extract-plugin插件
压缩css:optimize-css-assets-webpack-plugin’插件

Uglify是压缩js：new Uglify(), webpack4已经不需要了,
“scripts”: {
“build”: “webpack --mode production”
}
production模式下js会自动压缩

const MiniCssExtractPlugin = require("mini-css-extract-plugin");//提取css到单独文件的插件
const OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');//压缩css插件
 module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          MiniCssExtractPlugin.loader,//注意这边
          "css-loader"
        ]
      }
    ]
  }
   plugins: [
      new MiniCssExtractPlugin({
            filename: "css/[name].css",////都提到build目录下的css目录中
            chunkFilename: "[id].css"
        }),
        new OptimizeCssAssetsPlugin()
   ]

提取压缩结果