// checks existence of ID in markup
function checkID(idName) {
	if (document.getElementById(idName)) {
		return true;
	} else {
		return false;
	}
}

// shows a html block
function showMe(idName,displayWay) {
	if (checkID(idName)) {
		document.getElementById(idName).style.display=displayWay;
	}
}

function getClassName(idName) { 
	if (checkID(idName)) {
		return document.getElementById(idName).className;
	}
}

// hides a html block
function hideMe(idName) {
	if (checkID(idName)) {
		document.getElementById(idName).style.display="none";
	}
}

// hides a html block
function srcMe(idName,s) {
	if (checkID(idName)) {
		document.getElementById(idName).src=s;
	}
}

// changes a stylesheet class to a specified ID
function changeClass(idName,toClass) {
	if (checkID(idName)) {
		document.getElementById(idName).className=toClass;
	}
}

function navOn(idName) {
	if (idName == "nav1") {
		changeClass(idName,"first on");
	} else {
		changeClass(idName,"on");
	}
	if (checkID(idName+"left")) {
		srcMe(idName+"left","http://www.todaysparent.com/images/leftCurveOn.gif");
	}
	if (checkID(idName+"right")) {
		srcMe(idName+"right","http://www.todaysparent.com/images/rightCurveOn.gif");
	}
} 
function navOff(idName) {
	if (idName == "nav1") {
		changeClass(idName,"first");
	} else {
		changeClass(idName,"");
	}
	if (checkID(idName+"left")) {
		srcMe(idName+"left","http://www.todaysparent.com/images/leftCurve.gif");
	}
	if (checkID(idName+"right")) {
		srcMe(idName+"right","http://www.todaysparent.com/images/rightCurve.gif");
	}
}