Can we use AJAX call in Thingworx supported JavaScript editor?

My actual task is :

1) Execute a URL

2) This URL returns a string.

3) Parse that string & take required values.

For this, I have created a service & wrote following code :

var xmlhttp = new XMLHttpRequest();

xmlhttp.open("POST","http://115.112.176.88:9090/fleetvigil/jsp/maps/ForLocator.jsp?cid=girikandptc&vehicle=9665983265", true);

xmlhttp.send();

xmlhttp.onreadystatechange = function()

{

    if (xmlhttp.readyState == 4 && xmlhttp.status == 200)

    {

        var responseStr = xmlhttp.responseText;

        var result = responseStr;

    }

};

After executing this service I got error for :  var xmlhttp = new XMLHttpRequest();

Error is : ReferenceError: "XMLHttpRequest" is not defined. (UrlExe2#3)

Any help is very much appreciated.