jquery-limit-text.js

$.fn.extend({
	limitText: function(config){
		$(this).after('<div id="counter">Limit znaków: <span></span></div>');

		var limit        = typeof(config.limit) == 'undefined' ? this.attr('maxlength') : config.limit;
		var counter_hook = typeof(config.counter) == 'undefined' ? '#counter' : config.counter;

		$(counter_hook).data('value', limit);
		$(counter_hook).find('span').html(limit);

		$(this).on('keyup keydown', function(){
			if( $(this).length > limit )
			{
				this.value = this.value.substring(0, limit);
			}
			else
			{
				$(counter_hook).find('span').html(limit - $(this).val().length);
			}
		});
	}
});