//browser detection
var ns = (navigator.appName == "Netscape");//Netscape browser
var ns6 = false;
var ua = navigator.userAgent;
if (document.getElementById) ns6 = true; //Netscape 6 or above

//images arrays
var imgNamesOff = new Array("images/mnu_impress.gif", "images/kontakt1.gif", "images/gaestebuch1.gif", "images/mnu_english.gif", "images/mnu_config.gif", "images/musik1.gif", "images/home.gif", "images/mnu_agb.gif", "images/martin_s_moritz1.gif", "images/mnu_gaeste.gif", "images/info1.gif");
var imgNamesOn = new Array("images/mnu_impress_on.gif", "images/kontakt1_on.gif", "images/gaestebuch1_on.gif", "images/mnu_english_on.gif", "images/mnu_config_on.gif", "images/musik1_on.gif", "images/home_on.gif", "images/mnu_agb_on.gif", "images/martin_s_moritz1_on.gif", "images/mnu_gaeste_on.gif", "images/info1_on.gif");
var imgOff = new Array(imgNamesOff.length);
var imgOn = new Array(imgNamesOn.length);

//preload images
for (i=0; i<imgNamesOff.length; i++){
	imgOff[i] = new Image();
	imgOff[i].src = imgNamesOff[i];
	imgOn[i] = new Image();
	imgOn[i].src = imgNamesOn[i];
}

//mouseover
function swapIn(objName){
	var obj = eval("document." + objName);
	for(i=0; i<imgNamesOff.length; i++)
		if (obj.src == imgOff[i].src){
			obj.src = imgOn[i].src;
			break;
		}
}

//mouseout
function swapOut(objName){
	var obj = eval("document." + objName);
	for(i=0; i<imgNamesOn.length; i++)
		if (obj.src == imgOn[i].src){
			obj.src = imgOff[i].src;
			break;
		}
}

//trim leading and trailing spaces
function Trim(strToTrim) {
	while(strToTrim.charAt(0)==' '){strToTrim = strToTrim.substring(1,strToTrim.length);}
	while(strToTrim.charAt(strToTrim.length-1)==' '){strToTrim = strToTrim.substring(0,strToTrim.length-1);}
	return strToTrim;
}
		
//validate email address
function emailAddressIsValid(str){
	var emailAddressFormat = /^[a-zA-Z0-9._-]+@([a-zA-Z0-9.-]+\.)+[a-zA-Z0-9.-]{2,3}$/;
	if (!(emailAddressFormat.test(str))){
		return false;
	}
	return true;
}
<!-- Copyright Martin Moritz, Hamburg. All Rights Reserved. -->