preliminary/server.js

const express = require('express');
const webpack = require('webpack');
const webpackDevMiddleware = require('webpack-dev-middleware');

const app = express();
const config = require('./webpack.config.js');
const compiler = webpack(config);

app.use(webpackDevMiddleware(compiler,{
  publicPath:config.output.publicPath
}));

app.listen(3000,function(){
  console.log('app listening on port 3000...\n');
})