yarn add sass-loader node-sass

node_modules/react-scripts/config/webpack.config.js

  {
              test:/\.scss$/,
            http://www.cppcns.com  loaders: ['style-loader', 'css-loader', 'sass-http://www.cppcns.comloader']
            },    

const WorkboxWebpackPlugin = require('workbox-webpack-plugin')
plugins: [
        new MiniCssExtractPlugin({
            filename: '[name].css'
        }),
  http://www.cppcns.com      new WorkboxWebpackPlug编程客栈in.GenerateSW({
            clientsClaim:true,
            skipWaiting:tru编程客栈e
        })
    ],