jQuery - stick element to top upon scrolling

jquery.stickyelement.js

/* 
Stick element to top

Version 0.01

Usage:

	$("#product_preview_container").stickyElement({ // apply to element to stick.
		stopPoint: $("#products_see_more"), // integer or jquery element to stop fading at
		stopPointOffset: 100, // offset the stop point 
		stickThreshold: 89, // when to start sticking 
		topOffset: 0 
	})		

By Yuji Tomita
February 26, 2012.
*/
(function( $ ){
	$.fn.stickyElement = function(options) {
		defaultOptions = {
			stickThreshold: 0, // height of viewport to stick from
			topOffset: 0, // container top offset
			containerHeight: $(this).height(),
			stopPoint: null,
			stopPointOffset: 0
		};
		if (typeof options == 'object') {
			options = $.extend(defaultOptions, options);
		} else {
			options = defaultOptions;
		};


		var stickThreshold = options['stickThreshold']; 
		var topOffset = options['topOffset']; 

		var $fixedElement = this;
		var heightOfContainer = $fixedElement.height();

		// must stop before bar obscures all items
		var stopPoint = options['stopPoint'];
		if (isNaN(stopPoint)) {
			stopPoint = $(stopPoint).offset().top;
		};
		stopPoint =  stopPoint - heightOfContainer - options['stopPointOffset'];

		if (! this.data('initialized')) {
			// replace current element with height offsetter - but only once.
			var heightContainer = $('<div/>').css('height', heightOfContainer);
			this.parent().prepend(heightContainer);
			this.data('initialized', true);
		}
	
		$(window).unbind('scroll').scroll(function() {
			var top = $(window).scrollTop()
			// stick to top until features
			if (top >= stickThreshold) {
				// Viewport is lower than stick threshold pixels
				// -----------------------------------------------
				if (top >= stopPoint) {
						// viewport is lower than the stop point - stop.
					$fixedElement.css({
						top: stopPoint + topOffset - stickThreshold, // must subtract height of navbar
						position: 'absolute'
					});
				} else {
					// top is lower - keep at top of screen
					$fixedElement.css({
						top: topOffset,
						position: 'fixed'
					});
				}
			} else {
				// viewport is higher than threshold - keep at wherever it's supposed to be
				$fixedElement.css({
					top: '0px',
					position: 'absolute'
				});
			} // end scroll handling
		}).scroll() // end scroll sticking
	};
})( jQuery );