Yogesh,

 

Please check this sample code :

 

 <script type="text/javascript">
 function CuteWebUI_AjaxUploader_OnSelect(files)
 {
  for(var i=0;i<files.length;i++)
  {
   var file=files[ i ];
   if(file.FileSize!=-1)
   {
    if(file.FileSize>102400)
    {
     alert(file.FileName+" is larger then 100K");
     return false;
    }
   }
  }
 }
 </script>

 

This is a client validation and you should validate the file size again at server side event.

 

Regards,

Terry