set time out in ajax call while using core javascript

Question

I have a JavaScript function to call ajax. Now I need to add time out in this function like while calling service took more than defile time ajax call should time out and display a default message. I don't want to use Jquery in it.

here is my code:

AJAX = function (url, callback, params) {
        var dt = new Date();
        url = (url.indexOf('?') == -1) ? url + '?_' + dt.getTime() : url + '&_' + dt.getTime();
        if (url.indexOf('callback=') == -1) {
            ajaxCallBack(url, function () {
                if (this.readyState == 4 && this.status == 200) {
                    if (callback) {
                        if (params) {
                            callback(this.responseText, params);
                        } else {
                            callback(this.responseText);
                        }
                    }
                }
            });
        } else {
            var NewScript = d.createElement("script");
            NewScript.type = "text/javascript";
            NewScript.src = url + '&_' + Math.random();
            d.getElementsByTagName('head')[0].appendChild(NewScript);
        }
    },
    ajaxCallBack = function (url, callback) {
        var xmlhttp;
        if (window.XMLHttpRequest) {
            xmlhttp = new XMLHttpRequest();
        } else {
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        xmlhttp.onreadystatechange = callback;
        xmlhttp.open("GET", url, true);
        xmlhttp.send();
    }

Answer 1

Here's an example of how you can handle a timeout:

var xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", "http://www.example.com", true);

xmlHttp.onreadystatechange=function(){
   if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
      clearTimeout(xmlHttpTimeout); 
      alert(xmlHttp.responseText);
   }
}
// Now that we're ready to handle the response, we can make the request
xmlHttp.send("");
// Timeout to abort in 5 seconds
var xmlHttpTimeout=setTimeout(ajaxTimeout,5000);
function ajaxTimeout(){
   xmlHttp.abort();
   alert("Request timed out");
}

In IE8, You can add a timeout event handler to the XMLHttpRequest object.

var xmlHttp = new XMLHttpRequest();
xmlHttp.ontimeout = function(){
  alert("request timed out");
}

Use a javascript framework to do this though, i don't know why you're not using one, do you like uneccesary work? :)