ERROR in build.js from UglifyJs Unexpected token: punc (()

原因:使用了ES6的语法需要安装uglifyjs-webpack-plugin

1.安装

npm i -D uglifyjs-webpack-plugin

2.修改webpack.conf.js

//添加
const UglifyJsPlugin = require('uglifyjs-webpack-plugin')
//替换将
new webpack.optimize.UglifyJsPlugin({
        sourceMap: true,
        compress: {
            warnings: false
        }
}),
//替换为
new UglifyJsPlugin({
            "uglifyOptions":
                {
                    compress: {
                        warnings: false
                    },
                    sourceMap: true
                }
        }
),