webpack4的mode配置

// webpack.development.config.js
module.exports = {
+ mode: 'development'
- devtool: 'eval',
- plugins: [
-   new webpack.NamedModulesPlugin(), //用key来标识每一个模块，替代之前的0,1,2数组的方式
-   new webpack.NamedChunksPlugin(), //用key来标识每一个chunks取代0,1,2数组的方式
-   new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("development") }),
- ]
}

用key的方式便于我们调试观察代码

// webpack.production.config.js
module.exports = {
+  mode: 'production',
-  plugins: [
-    new UglifyJsPlugin(/* ... */), //压缩代码
-    new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("production") }),
-    new webpack.optimize.ModuleConcatenationPlugin(),
-    new webpack.NoEmitOnErrorsPlugin() //出现错误也继续编译
-  ]
}