Simple drop-downs using YAHOO.util.Dom.isAncestor

Dylan — Sat, 02 May 2009 17:03:01 +0000

The Yahoo! User Interface Library (YUI) has a bunch of very nifty little methods to make complex tasks easier. One that immediately stood out to me was isAncestor, as I can attest first-hand to the cross-browser troubles when trying to detect ancestry in the DOM. Although a very basic concept, most drop-down code often becomes bloated or restrictive. I’m not advocating the use of JavaScript drop-downs over a CSS method, but there are some added benefits of using JS to achieve this effect:

Clean markup, no need for conditional comments
The ability to animate show and hide events
Added styling opportunities, won’t break so long as the nested list structure remains in tact

Below is a simple example of how to use YUI’s isAncestor to create flyout menus with HTML and CSS.

(function() {
	function mouseover(e) {
		var menu = this.getElementsByTagName('ul')[0];
		YAHOO.util.Dom.setStyle(menu, 'display', 'block');
	};

	function mouseout(e) {
		if (!YAHOO.util.Dom.isAncestor(this, e.relatedTarget) || e.relatedTarget == document.getElementsByTagName('html')[0]) {
			var menu = this.getElementsByTagName('ul')[0];
			YAHOO.util.Dom.setStyle(menu, 'display', 'none');
		}
	};
	YAHOO.util.Event.on(YAHOO.util.Dom.get('nav').getElementsByTagName('li'), 'mouseover', mouseover);
	YAHOO.util.Event.on(YAHOO.util.Dom.get('nav').getElementsByTagName('li'), 'mouseout', mouseout);
})();

See Example »

If you need something more complex, see the YUI MenuCreator page.

Dylan Butler » San Diego Freelance Web Development and Consultation » isancestor

Simple drop-downs using YAHOO.util.Dom.isAncestor