Learn Uploadify Dynamic File Extension

Requirement: To change the file extension depending on the value of a dropdown box.

The code will explain how this can be achieve.

<script type="text/javascript">
$(document).ready(function() { 
 var fileExt = "";
 var fileDesc = "";
 var leftSelected = $("#categories option:selected");
 if(leftSelected.val() == "PRI") {
  fileExt = "*.jpg;*.jpeg;*.gif;*.doc;*.docx;*.pdf";
  fileDesc = "Allowed Files (.JPG, .JPEG, .GIF, .DOC, .DOCX, .PDF)";
 } else if(leftSelected.val() == "AUD") {
  fileExt = "*.mp3;*.wav";
  fileDesc = "Allowed Files (.MP3, .WAV)";
 } else if(leftSelected.val() == "VID") {
  fileExt = "*.flv;*.mpg;*.mp4;*.avi";
  fileDesc = "Allowed Files (.FLV, .MPG, .MP4, .AVI)";
 } else if(leftSelected.val() == "SMS") {
  fileExt = "*.html,*.htm,*.doc;*.docx;*.pdf";
  fileDesc = "Allowed Files (.HTML, .HTM, .DOC, DOCX, PDF)";
 }
 $('#custom_file_upload').uploadify({
  'uploader'       : "uploadify.swf",
    'script'         : "uploadify.php",
    'cancelImg'      : "cancel.png",
    'checkScript'   : "uploadifycheck.php",
    'folder'         : "",
    'pagePath'    : "",
    'multi'          : true,
    'auto'           : false,    
    'fileExt'  : fileExt,
    'fileDesc'  : fileDesc,
    'queueID'        : 'custom-queue',
    'queueSizeLimit' : 5,
    'displayData'    : 'percentage',
    'scriptData'     : {'categories': $('#categories').val()}, //send a post variable in uploadify.php
    'onSelectOnce'   : function(event,data) {
     $('#status-message').text(data.filesSelected + ' files have been added to the queue.');
  },
  'onAllComplete'  : function(event,data) {
     $('#status-message').text(data.filesUploaded + ' files uploaded, ' + data.errors + ' errors.');
     location.reload();
  }
 });
</script>

Note: Need to link with jquery.js