27. webpack中使用babel

webpack.config.js

module.exports = {
    mode: 'development',
    devtool: 'source-map',
    entry: {
        index: './src/index.js'
    },
    module: {
        rules: [
            { test: /\.js$/, use: 'babel-loader' }
        ]
    }
}

在webpac配babel-laoder,同时需要配置babel的预设

.babelrc

{
    "presets": [
        ["@babel/preset-env", {
            "useBuiltIns": "usage",
            "corejs": 3
        }]
    ]
}

顺序是