JavaScript: jQuery Persistant Navigation Menu

persnav.js

/**
 * Name:            Persistant Navigation Menu
 * Type:            jQuery Plugin - jQuery v1.7.2
 * Description:     Makes any navigation menu or DOM element persistant
 * Author:          Billy Onjea  (blog.istocode.com)
 * --------------------------------------------------------------------
 * Minimum CSS Classes:
 * --------------------------------------------------------------------
 * .persisting { 
 *     position: fixed;
 *     top: 0;
 *     z-index: 990; 
 *     visibility: hidden;
 *  }
 * .visible { visibility: visible !important; }
 * --------------------------------------------------------------------
 * Call it like so:  $('.menu').Persnav();
 * --------------------------------------------------------------------
**/
(function($) {
	var pnav = {
	    persist: function(thisClone) {
	        return this.each(function(i, domEl) {
		    var top = $(this).offset().top; 

		    if ($(window).scrollTop() > top) {
		        thisClone.addClass('visible');
		    } else {
		        thisClone.removeClass('visible');
		    }
		});
	    }
	};

	$.fn.Persnav = function() {
	    var $this = $(this);
	    var thisClone = $this.clone().addClass('persisting');

	    $this.before(thisClone);

	    $(window).scroll(function() {
	        return pnav['persist'].call($this, thisClone);
	    });
	};

})(jQuery);