webpack打包高级es语法示例：

默认情况下，webpack打包js不会做任何转换和编译 而至原样输出，所以让浏览器支持es高级语法需要用babel来转换。

npm install --save-dev @babel/preset-env 
@babel/core 
babel-loader

webpack.config.js
const miniCssExtractPlugin = require('mini-css-extract-plugin')

module.exports = {
    entry: './src/index.js',
    output: {
        filename: 'main.js',
    },
    mode: 'development', // 或者 'production'
    module: {
        rules: [
            {
                test: /\.js/,
                exclude: /(node_modules)/,
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: ['@babel/preset-env']
                    }
                }
            }
    ]
    }
}

src/index.js
const fn = (a) => {
    console.log('fn')
    return a+1
}
fn(2)

const promise = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log('promise')
            resolve('success')
        }, 2000);
    })
}
(async()=>{
    await promise()
    console.log('aaa')
})()