Lapegna.comUX, Design & Development of games, iOS apps, touch screen kiosks and web applications

/**
* setInternalLinks
* Searches the page for any internal links and converts them to animated automatic scrolls
*/
function setInternalLinks()
{
	// grab all anchor links on the page
	var anchors = document.getElementsByTagName('a');
 
	for (var i = 0; i < anchors.length; i++) {
		var a = anchors[i];
 
		if (a.href && a.href.indexOf("#") != -1  // href has #
		   && ((a.pathname == location.pathname) || ('/' + a.pathname == location.pathname)) // path name of url is same as current
		   && (a.search == location.search)) { // query string of url is same as current
			var aName = a.href.substr(1, a.href.length - 1);
			a.onclick = function (e) {
				// checks if the caller event e exists and grabs the target (mozilla + webkit). Grabs the IE equivalent if not.
				var target = e ? e.target : event.srcElement;
				// the anchor name
				var anchorName = target.hash;
				// cut out the hash mark
				anchorName = anchorName.substr(1, anchorName.length - 1);
				// grab all the anchors on the page again
				anchors = document.getElementsByTagName('a');
 
				for (var j = 0; j < anchors.length; j++) {
					if (anchors[j].name == anchorName) {
						// found the right anchor. scroll to it!
						scrollToYOffset(anchors[j].offsetTop);
					}
				}
			};
		}
	}
}

/**
* scrollToOffset
*
* @param yOffset	The vertical offset to scroll to
*/
function scrollToYOffset(iTargetY)
{
	// if the target is negative set it to 0
	iTargetY = iTargetY < 0 ? 0 : iTargetY;
 
	var frameInterval = 20; // 20 milliseconds per frame
 
	var totalTime = 750;
	// current scroll position: checks if window.pageYOffset exists (webkit + mozilla). If not, set's it to the IE equivalent
	var startY = window.pageYOffset ? window.pageYOffset : window.document.body.scrollTop;
 
	var d = iTargetY - startY; // total distance to scroll
	var freq = Math.PI / (2 * totalTime); // frequency
	var startTime = new Date().getTime();
 
	var tmr = setInterval(
		function () {
			// check the time that has passed from the last frame
			var elapsedTime = new Date().getTime() - startTime;
 
			if (elapsedTime < totalTime) { // are we there yet?
				var f = Math.abs(Math.sin(elapsedTime * freq));
				window.scrollTo(0, Math.round(f*d) + startY);
			} else {
				clearInterval(tmr);
				window.scrollTo(0, iTargetY);
			}
		}
	, frameInterval);
}