server.js file from the Lexi WordPress theme: https://github.com/lamosty/lexi/blob/master/server.js

server.js

var webpack = require('webpack');
var WebpackDevServer = require('webpack-dev-server');
var config = require('./webpack.config');

new WebpackDevServer(webpack(config), {
    publicPath: config.output.publicPath,
    hot: true,
    historyApiFallback: true,
    stats: {
        colors: true
    }
}).listen(3000, 'localhost', function(err) {
    if (err) {
        console.log(err);
    }

    console.log('Listening at localhost:3000');
});