vk-publics-get-ajax-looped

function getPublics(userId,callback) {
  var xhr = new XMLHttpRequest();

  var body = 'act=load_idols&al=1&oid=' + userId;

  xhr.open("POST", 'https://vk.com/al_fans.php', true)
  xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');

  xhr.onreadystatechange = function() {
    if (this.readyState == 4) {
    	if (this.status == 200) {
			var vkData = this.responseText;
			console.log('Got DATA:' + vkData.substring(0,100) + '...');

			if (vkData.indexOf('<!json>') !== -1) {
				var publics = vkData.substr(vkData.indexOf('<!json>') + 7);
				var publicsArr = JSON.parse(publics);
				if (Array.isArray(publicsArr))
			 		callback(publicsArr)
			 	else {
			 		callback('data parse error')
			 	}
			} else {
				callback('no json error')
			}
			
			
    	} else {
    		callback('response error')
    	}
  	};
  }
  xhr.send(body);

}

var users = [];
var userId = 1;
var lastId = 1000;


var interval = (min, max) =>
  Math.floor(Math.random() * (max - min + 1)) + min; //in ms

 var t0, t1;

function storeUsersPublics() {
	if (userId === 1) t0 = performance.now();
	setTimeout(() => {
		getPublics(userId, (data) => {
			if (typeof data !== 'string') { // not error
				users.push({
					id: userId,
					publics: data
				});

				console.log('Successfully stored data of id' + userId);

				if (userId < lastId) {
					userId++;
					storeUsersPublics();
				} else {
					 t1 = performance.now();
					console.log("Time took " + (t1 - t0) + " milliseconds.")
				}
			} else { // error
				users.push({
					id: userId,
					publics: data
				});
				console.log('ERROR: ' + data + ' of id' + userId);
				if (userId < lastId) {
					userId++;
					storeUsersPublics();
				} 
			}

		});
	}, interval(10, 100))

}