Ajax Basic Question

[ajaxiskey]

Can someone please explain the complete ajax request in high detail.

 

0: request not initialized

1: server connection established

2: request received

3: processing request

4: request finished and response is ready

 

The point of me asking this question is that I must know when the PHP code on the page I called has finished being processed...

[JonnoTheDev]

It is complete when the readyState is 4 (as you have showed in your document). There will also be a status of 200. Example:

// start ajax object
var req = Inint_AJAX();
     // check request status
     req.onreadystatechange = function () { 
          // request is complete
          if (req.readyState==4) {
               // status ok
               if (req.status==200) {
                    alert('finished processing');
               } 
          }
     };
     // make connection
     req.open("GET", "/phpfile.php"); 
     // set header
     req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=iso-8859-1");
     // send value
     req.send(null); 

[ajaxiskey]

When does the php code on the requested page start running, and end running... readyState wise?

[JonnoTheDev]

When does the php code on the requested page start running, and end running... readyState wise?

As soon as the javascript function containing the request is called, usually through an event handler such as onClick() i.e the user clicks a button. When the readyState value is 4 the script has completed.