scrollWithoutJquery.js

(function () {
	var speed = 500;
	var moving_frequency = 15; // Affects performance !
	var links = document.getElementsByTagName('a');
	var href;
	for (var i = 0; i < links.length; i++) {
		href = (links[i].attributes.href === undefined) ? null : links[i].attributes.href.nodeValue.toString();
		if (href !== null && href.length > 1 && href.substr(0, 1) == '#') {
			links[i].onclick = function () {
				var element;
				var href = this.attributes.href.nodeValue.toString();
				if (element = document.getElementById(href.substr(1))) {
					var hop_count = speed / moving_frequency
					var getScrollTopDocumentAtBegin = getScrollTopDocument();
					var gap = (getScrollTopElement(element) - getScrollTopDocumentAtBegin) / hop_count;

					for (var i = 1; i <= hop_count; i++) {
						(function () {
							var hop_top_position = gap * i;
							setTimeout(function () {
								window.scrollTo(0, hop_top_position + getScrollTopDocumentAtBegin);
							}, moving_frequency * i);
						})();
					}
				}

				return false;
			};
		}
	}

	var getScrollTopElement = function (e) {
		var top = 0;

		while (e.offsetParent != undefined && e.offsetParent != null) {
			top += e.offsetTop + (e.clientTop != null ? e.clientTop : 0);
			e = e.offsetParent;
		}

		return top;
	};

	var getScrollTopDocument = function () {
		return document.documentElement.scrollTop + document.body.scrollTop;
	};
})();