(function($){ 
     $.fn.extend({  
         limit: function(limit,element) {
            var interval, f;
            var self = $(this);     
            $(this).focus(function(){
                interval = window.setInterval(substring,100);
            });
            $(this).blur(function(){
                clearInterval(interval);
                substring();
            });
            substringFunction = "function substring(){ var val = $(self).val();var length = val.length;if(length > limit){$(self).val($(self).val().substring(0,limit));}";
            if(typeof element != 'undefined')
                substringFunction += "if($(element).html() != limit-length){$(element).html((limit-length<=0)?'0':limit-length);}"
            substringFunction += "}";
            eval(substringFunction);
            substring();
        } 
    }); 
})(jQuery);