Viewport Event jQuery Plugin

jquery.viewport-event.js

/*
Example:
$('div')
	.viewport()
	.one('viewport', function() {
		$(this).addClass('view');	
	});
*/
(function($) {
	$.fn.viewport = function() {
		var	_this = $(this), _document = $(document), elem, 
			event = "viewport",
			datakey = "vp",
			vpTop, vpLeft, vpRight, vpBottom,
			elTop, elLeft, elRight, elBottom,
			detect = function() {
				elem		= $(this);
				elTop		= elem.offset().top;
				elLeft		= elem.offset().left;
				elBottom	= elTop + elem.height();
				elRight		= elLeft + elem.width();
				var is		= !(
					elTop > vpBottom ||
					elBottom < vpTop ||
					elRight < vpLeft ||
					elLeft > vpRight
				);
				if ( is && elem.data(datakey) != is )
					elem.trigger(event);
				elem.data(datakey. is);
			};
		jQuery(window).bind('scroll resize', function() {
			vpTop		= _document.scrollTop();
			vpLeft		= _document.scrollLeft();
			vpRight		= vpLeft + (window.innerWidth ? window.innerWidth : document.documentElement.clientWidth  ? document.documentElement.clientWidth  : document.body.offsetWidth);
			vpBottom	= vpTop + (window.innerHeight ? window.innerHeight : document.documentElement.clientHeight  ? document.documentElement.clientHeight  : document.body.offsetHeight);
			_this.each(detect);
		}).trigger('scroll');
		return _this;
	}
})(jQuery);