在webpack.prod.conf.js 文件中将设置修改为
先全局找到 UglifyJsPlugin
然后修改为：
new UglifyJsPlugin({
uglifyOptions: {
compress: {
warnings: false,
drop_debugger: true,
drop_console: true
}
},
sourceMap: config.build.productionSourceMap,
parallel: true
})