'use strict';

let config = require('config');
let express = require('express');
let logger = require('morgan');

let app = new express();

// ## Middleware

app.use(logger('dev'));
app.use(express.static(`${__dirname}/public`));

// ## Routes
if (config.env == 'dev') {
  let webpackMiddleware = require('webpack-dev-middleware');
  let webpack = require('webpack');
  let webpackConfig = require('./webpack.config.js');
  app.use(webpackMiddleware(webpack(webpackConfig), {}));
}

app.listen(config.port, () => console.log(`Server running on port ${config.port}...`));

var config = require('config');
var express = require('express');
var logger = require('morgan');

var app = new express();

// ## Middleware

app.use(logger('dev'));
app.use(express.static(__dirname + '/public'));

// ## Routes
if (config.env == 'dev') {
  var webpackMiddleware = require('webpack-dev-middleware');
  var webpack = require('webpack');
  var webpackConfig = require('./webpack.config.js');
  app.use(webpackMiddleware(webpack(webpackConfig), {}));
}

app.listen(config.port, function () {
  console.log('Server running...');
});
--- 
+++ 
@@ -1,22 +1,22 @@
-var config = require('config');
-var express = require('express');
-var logger = require('morgan');
+'use strict';
 
-var app = new express();
+let config = require('config');
+let express = require('express');
+let logger = require('morgan');
+
+let app = new express();
 
 // ## Middleware
 
 app.use(logger('dev'));
-app.use(express.static(__dirname + '/public'));
+app.use(express.static(`${__dirname}/public`));
 
 // ## Routes
 if (config.env == 'dev') {
-  var webpackMiddleware = require('webpack-dev-middleware');
-  var webpack = require('webpack');
-  var webpackConfig = require('./webpack.config.js');
+  let webpackMiddleware = require('webpack-dev-middleware');
+  let webpack = require('webpack');
+  let webpackConfig = require('./webpack.config.js');
   app.use(webpackMiddleware(webpack(webpackConfig), {}));
 }
 
-app.listen(config.port, function () {
-  console.log('Server running...');
-});
+app.listen(config.port, () => console.log(`Server running on port ${config.port}...`));
Use ES2015 support in node 4.x
