title: if (xmlhttp.readyState == 4 && xmlhttp.status == 200) this condition is not working
body: <p>Actually I am working on a chatbox....But It doesn't meet this condition.
     Here is the code</p>
  
  <pre><code>function submitChat() {
    if (form1.users.value == "" || form1.messege.value == "") {
      alert("Please fill the all feild");
      return;
    }
    var users = form1.users.value;
    var messege = form1.messege.value;
    var xmlhttp = new XMLHttpRequest();
    xmlhttp.onreadystatechange = function() {
      //Here is the problem may be
      if (xmlhttp.readyState == 4 &amp;&amp; xmlhttp.status == 200) {
        document.getElementByID('shouts').innerHTML = xmlhttp.responseText;
      }
    }
    xmlhttp.open('GET', 'process.php?users' + users + '&amp;messege' + messege, 'true');
    xmlhttp.send();
  </code></pre>
  
  <p>Here these variable shows undefined..</p>
  
  <pre><code>$users = $_REQUEST['users'];
  $messege =  $_REQUEST['messege'];
  </code></pre>