(function($) { /** * Copyright 2012, Digital Fusion * Licensed under the MIT license. * http://teamdf.com/jquery-plugins/license/ * * @author Sam Sehnert * @desc A small plugin that checks whether elements are within * the user visible viewport of a web browser. * only accounts for vertical position, not horizontal. */ $.fn.visible = function(partial) { var $t = $(this), $w = $(window), viewTop = $w.scrollTop(), viewBottom = viewTop + $w.height(), _top = $t.offset().top, _bottom = _top + $t.height(), compareTop = partial === true ? _bottom : _top, compareBottom = partial === true ? _top : _bottom; return ((compareBottom <= viewBottom) && (compareTop >= viewTop)); }; })(jQuery);