ES6降级ES5

1. cnpm install babel-loader babel-core babel-preset-env --save-dev
   此处有个bug，babel-loader版本太高，我又将它降回7.1.4

2.修改webpack.config.js

{
    test:/\.js$/,
    exclude:/(node_modules|bower_components)/,//排除掉node_module目录
    use:{
        loader:'babel-loader',
        options:{
            presets:['env'] //转码规则
        }
    }
}

babel-polyfill 来提供低版本浏览器中的不支持API

1. cnpm install babel-polyfill --save-dev
2. 修改webpack.config.js的entry属性

entry: ['babel-polyfill','./src/index.js'],