jquery.val_change.js

// watches a text input/area and triggers a change event as soon as it changes. Doesn't wait for blur.
// Doesn't loop unless a relevant element is focused

(function($){
  $.fn.extend({
    val_change: function(callback){
      var interval;
      var $this = $(this);
      $this.focus(function(){
        val last_val, current_val;
        interval = setInterval(function(){
          var current_val = $this.val();
          if (last_val !== current_val) {
            $this.triggerHandler('val_change');
            last_val = current_val;
          }
        }, 16);
      }).blur(function(){
        $this.unbind('val_change');
        clearInterval(interval);
      }).bind('val_change', callback);
      return $this;
    }
  });
})(jQuery);