function addLoadEvent(func) {
	var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function() {
			oldonload();
			func();
		}
	}
}

function showSectionId(id) {
	var divs = document.getElementsByTagName("div");
	for (var i=0; i<divs.length; i++) {
		if(divs[i].className.indexOf("menu")== -1) continue;
		if(divs[i].getAttribute("id") != id && divs[i].getAttribute("id") != "content") {
			divs[i].style.display = "none";
		}else {
			divs[i].style.display = "block";
		}
	}
}

function prepareMenuNav() {
	if (!document.getElementsByTagName) return false;
	if (!document.getElementById) return false;
	if (!document.getElementById("menuNav")) return false;
	var menuNav = document.getElementById("menuNav");
	var links = menuNav.getElementsByTagName("a");
	var firstTime = true;
	for (var i=0; i < links.length; i++) {
		var sectionId = links[i].getAttribute("href").split("#")[1];
		if (!document.getElementById(sectionId)) continue;
		document.getElementById(sectionId).style.display = "none";
		if (firstTime) {
			var initialMenu = links[0].getAttribute("href").split("#")[1];
			document.getElementById(initialMenu).style.display = "block";
		}
		links[i].destination = sectionId;
		links[i].onclick = function() {
			showSectionId(this.destination);
			return false;
		}
	}
}

addLoadEvent(prepareMenuNav);