7.CleanwebpackPlugin

1.npm install--save-dev clean-webpack-plugin

const CleanWebpackPlugin=require('clean-webpack-plugin');

const path=require('path');

module.exports={

entry:'index.js',

output:{

       path:path.resolve(__dirname,'./dist'),

     filename:'index_bundle.js'

    },

plugins: [ 

             new CleanWebpackPlugin(['dist'])//自动删除打包之前的dist文件目录

           ]

};