A minimal ‘slow’ server to test API calls with callbacks and promises

slowServer.js

'use strict';

/*
* Before you start, make sure you've done the following:
* mkdir slowServer
* cd slowServer
* $ npm init
* $ npm install express --save
* Then copy this file to the slowServer directory
*/

const express = require('express');
const app = express();

app.get('/', (req, res)=> {

	new Promise((resolve, reject)=> {
		let now = new Date();
		let nowStr = now.toUTCString();

		// simulate waiting by doing some waiting...
		setTimeout( ()=> {
			
			let passed = new Date();
			let passedStr = passed.toUTCString();
			
			let diff = passed-now;

			let data = {
				serverTime: nowStr,
				responseTime: passedStr,
				difference: diff + " μs"
			};

			resolve(data);
			
		}, 2000);

	}).then( (json)=> {
		res.setHeader('Content-Type', 'application/json');
		res.status(200).send(json);	
	});

});

const port = 1337;
app.listen(port, ()=> console.log('Slow server running @ port: '+ port) );

/*
* Start by running `node slowServer.js`
* Then open your favourite internet browser and go to http://localhost:1337
*/