Simplest way to write this AJAX call

I need to send an ajax request to a webserver "http://examples.com/ajax" the response will be the html of a <div> and it will be inserted to an existing <div id="holder">开发者_Python百科. What's the simplest, smallest way to write this in javascript? without using jQuery?

It only needs to support the latest version of chrome.

var req = new XMLHttpRequest();

req.onreadystatechange = function() {
  //Is request finished? Does the requested page exist?
  if(req.readyState==4 && req.status==200) {   
    //Your HTML arrives here
    alert(req.responseText);  
  }
}

req.open("GET","http://examples.com/ajax.php",true)  //true indicates ASYNCHRONOUS
req.send(null);

This solution uses get, so you've got to add variables using ? and & to your URL (e.g. http://examples.com/ajax.php?foo=bar&blah=blee.

If you want to do it using post, run a few with get and then this article is useful.