Question

I have a problem with my AJAX script, I put in some alerts to see where the problem lies, here is my script:

<script language="javascript" type="text/javascript">     function positionUpdate(var1, var2){         alert ("1");         var queryString = "?var1=" + var1 + "&var2=" + var2;         alert ("2");         ajaxRequest.open("GET", "position_update.php" + queryString, true);         alert ("3");         ajaxRequest.send(null);         alert ("4");     } </script> 

Alert 3 doesn’t show up when I run it so it looks like the problem is with this line but I don’t know what it is:

ajaxRequest.open("GET", "position_update.php" + queryString, true); 

Thanks, Stanni

Answer 1

You haven’t instantiated the ajaxRequest object yet. At that point, it’s still undefined.

You’ll need to have this first:

try{         // Opera 8.0+, Firefox, Safari         ajaxRequest = new XMLHttpRequest();     } catch (e){         // Internet Explorer Browsers         try{             ajaxRequest = new ActiveXObject('Msxml2.XMLHTTP');         } catch (e) {             try{                 ajaxRequest = new ActiveXObject('Microsoft.XMLHTTP');             } catch (e){                 // Something went wrong                 alert('Your browser broke!');                 return false;             }         }     }