problem with JS functions

function getLikeElements(tagName, attrName, attrValue){
		var startSet;
		var endSet = new Array( );
		if (tagName){
			startSet = document.getElementsByTagName(tagName);    
		} else {
			startSet = (document.all) ? document.all : 
            document.getElementsByTagName("*");
		}
		if (attrName){
			for (var i = 0; i < startSet.length; i++) {
				if (startSet[i].getAttribute(attrName)) {
					if (attrValue) {
						if (startSet[i].getAttribute(attrName) == attrValue) {
							endSet[endSet.length] = startSet[i];
						}
					} else {
						 endSet[endSet.length] = startSet[i];
					}
				}
			}
		} else {
			endSet = startSet;
		}
		return endSet;
	}


	function getElementPosition(elemID)
	{
		var offsetTrail = document.getElementById(elemID);
		var offsetLeft = 0;
		var offsetTop = 0;
		while (offsetTrail)
		{
			offsetLeft += offsetTrail.offsetLeft;
			offsetTop += offsetTrail.offsetTop;
			offsetTrail = offsetTrail.offsetParent;
		}
		if (navigator.userAgent.indexOf("Mac") != -1 && typeof document.body.leftMargin != "undefined")
		{
			offsetLeft += document.body.leftMargin;
			offsetTop += document.body.topMargin;
		}
		return {left:offsetLeft, top:offsetTop};
	}