Autosave jQuery plugin

typed.jquery.js

//  jQuery plugin to easily implement autosave
//  
//
//
//
     ;(function($) {
       $.fn.typed = function(settings) {
       
         var config = {
            'callback': function(){},
            wait : 750
         };
         if (settings) $.extend(config, settings);
     
         this.each(function(){
                $(this).attr('old-val', $(this).val());
                var that = this
                function save(){
                   var val = $(that).val()
                   var old_val = $(that).attr('old-val');
                   if (val != old_val) {
                      config.callback.call(that)
                      $(that).attr('old-val', val )
                   }
                }
                var t;
                $(this).keydown(function(){
                    clearTimeout(t)                  
                })
                $(this).keyup(function(){
                    clearTimeout(t)
                    t = setTimeout(save, config.wait);
                })
            })
         return this;
       };
     })(jQuery);
     
//example usage       
   // $('.datepicker').typed({callback : change_form});