XMLHttpRequest Reference

XMLHttpRequest Reference Cheat Sheet

Now that we've covered the use of these objects, this cheatsheet will help you as your code your applications. Remember to bookmark this and refer back to it as you code your AJAX applications.

Quick start

function ajax_request(url, data, callback) {
  try {
    xhrobj = new XMLHttpRequest();
  } catch (e) {
    try {
      xhrobj=new ActiveXObject("Msxml2.XMLHTTP");
    } catch (e) {
      xhrobj=new ActiveXObject("Microsoft.XMLHTTP");
    }
  }
  
  xhrobj.open("GET", url);
  xhrobj.setRequestHeader("X-Requested-With", "XMLHttpRequest"); 
  
  xhrobj.onreadystatechange = function() {
    if (xhrobj.readyState == 4 && xhrobj.status == 200) {
      callback(xhrobj.responseText);
    }
  };
  xhrobj.send(data);
}

Examples:

ajax_request("backend.php", null, function(data){ return });
ajax_request("backend.php", null, function(data){ alert(data); });
ajax_request("backend.php?var1=value&var2=value", null, function(data){ return });

You must specify a callback function. However, the callback function does not need to do anything and can simply return. If you need to send data in the message body (e.g. for some remote procedure calls), substitute the null in the second parameter with a string of data.

XMLHttpRequest Reference

Methods

Properties