Server side:

index.html

webpack.config.js:
module.exports= {

devtool: "eval-source-map",
entry: "./src/index.js",
output: {
    path: __dirname+ "/src/dist",
    filename: "bundle.js"
},
mode: "development",
module: {
    rules: [
        {
            test: /(\.jsx|\.js)$/,
            use: {
                loader: "babel-loader",
                options: {
                    presets: ["env","react"]
                }
            },
            exclude: /node_modules/
        },
        {
            test: /(\.css|\.sass)$/,
            use: [
                {
                    loader: "style-loader"
                },
                {
                    loader: "css-loader"
                },
                {
                    loader: "sass-loader"
                }
            ]
        }
    ]
}

}