index.js

var https = require('https');
var Notification = require('node-notifier');
var CronJob = require('cron').CronJob;

var storesUrl = 'https://reserve.cdn-apple.com/GB/en_GB/reserve/iPhone/stores.json';
var stockUrl = 'https://reserve.cdn-apple.com/GB/en_GB/reserve/iPhone/availability.json';

var stockLastUpdated;

var stores;
var stock;
var storeNameMap = {};

new CronJob('*/2 * * * *', function() {
	console.log("Checking stock in the UK stores...")
	console.log("");

	https.get(storesUrl, function(res) {
		var body = '';
		res.on('data', function(chunk) {
			body += chunk;
		});
		res.on('end', function() {
			stores = JSON.parse(body).stores;
			listAvailableStock();
		});
	}).on('error', function(e) {
		  console.log("Got error for URL "+storesUrl+" : ", e);
	});

	https.get(stockUrl, function(res) {
		var body = '';
		res.on('data', function(chunk) {
			body += chunk;
		});
		res.on('end', function() {
			stock = JSON.parse(body);
			stockLastUpdated = new Date(res.headers["last-modified"]);
			delete stock.updated;
			listAvailableStock();
		});
	}).on('error', function(e) {
		console.log("Got error for URL "+storesUrl+" : ", e);
	});
}, null, true);

function listAvailableStock() {
	var notifier = new Notification();
	if (stores != null && stock != null) {

		for (var i in stores) {
			var store = stores[i];
			var storeName = store.storeName;
			var storeNumber = store.storeNumber;
			storeNameMap[storeNumber] = storeName;
		}

		var foundStock = false;

		for (var storeNumber in stock) {
			var stockEntry = stock[storeNumber];
			var storeName = storeNameMap[storeNumber];
			for (var s in stockEntry) {
				if (stockEntry[s] == true) {
					foundStock = true;
					// console.log(storeName + " has stock!");
					notifier.notify({
						title: 'Stock found!',
						message: storeName + " has stock!"
					});
					break;
				}
			}
		}

		if (!foundStock) {
			notifier.notify({
				title: 'No stock anywhere!',
				message: "Dang."
			});
		}

		console.log("");
		console.log("Go to https://reserve.cdn-apple.com/GB/en_GB/reserve/iPhone/availability for more info");
		console.log("");
		console.log("Last updated: " + stockLastUpdated.getHours()+":"+stockLastUpdated.getMinutes());

	}
}

how to use this script?thank you