Asynchronous request

async_timer.js

    // asynchronous request by using timer
    // but not working when setInterval with 500, 100 < 1000
    var messages = [];
    var timer  = setInterval(myTimer, 1000);

    function myTimer() {
        $.ajax({
                url: 'https://www.zalora.sg/ajax/catalog/justforyou/?feedName=recentlyviewed&brandName=&size=20&category=&userId=10214339066013667&engine=datajet'
            })
            .done(function(msg){
                if(messages.indexOf(msg) == -1) {
                    messages.push(msg);
                }
                if (messages.length >= 3) {
                    clearInterval(timer);
                        alert(messages.toString());
                  $("#result").append(messages.join('\n'));
                }
            })
            .fail(function() {
                alert( "can not get message from zalora");
            });
    }