How to abort XMLHttpRequest if the connection timeout?

Question

I'm experiencing an issue with XMLHttpRequest. If there is no Internet connection, my request is not timing out and thus freezing the browser. Here is the request code:

 var jsonData = new XMLHttpRequest();
 jsonData.open('GET', urltest, false);
 jsonData.Timeout = 100;
 jsonData.send(null);
 if(jsonData.status == 200) {
     alert(jsonData.statusText);
 }else{
     alert(jsonData.statusText);
 }

How do I abort the request if the server doesn't respond?