jQuery.fn.isUrl = function() {
   value = $(this).val();
   return !value.match(/^(https?|ftp):\/\/[A-Z0-9](\.?[A-Z0-9能謁[A-Z0-9_\-能謁*)*(\/([A-Z0-9能謁[A-Z0-9_\-\.能謁*)?)*(\?([A-Z0-9能謁[A-Z0-9_\-\.%\+=&能謁*)?)?$/i);
   }
jQuery.fn.isEmpty = function() {
   value = $(this).val();
   return value == "";
   }