webpack4的mode配置

1. webpack提供一些默認的配置 這個配置能夠經過mode來制定
2. 可選production（默認）/ development / none
3. development配置

   // webpack.development.config.js
   module.exports = {
   + mode: 'development'
   - devtool: 'eval',
   - plugins: [
   -   new webpack.NamedModulesPlugin(), //用key來標識每個模塊，替代以前的0,1,2數組的方式 -   new webpack.NamedChunksPlugin(), //用key來標識每個chunks取代0,1,2數組的方式 -   new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("development") }),
   - ]
   }

   用key的方式便於咱們調試觀察代碼

4. production配置

   // webpack.production.config.js
   module.exports = {
   +  mode: 'production',
   -  plugins: [
   -    new UglifyJsPlugin(/* ... */), //壓縮代碼
   -    new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("production") }),
   -    new webpack.optimize.ModuleConcatenationPlugin(),
   -    new webpack.NoEmitOnErrorsPlugin() //出現錯誤也繼續編譯
   -  ]
   }