var W3CDOM = (document.getElementsByTagName && document.createElement);

window.onload = function (){
	for (var i=0;i<document.forms.length;i++){
		frmID = document.forms[i].id
		document.getElementById(frmID).onsubmit = function (){
			return validate(this);
		}
	}
}
function validate(frm) {
	validForm = true;
	firstError = null;
	errorstring = '';
	var x = frm.elements;
	for (var j=0;j<x.length;j++){
		if (x[j].className.indexOf('fieldRequired') > -1 && !x[j].value){
			writeError(x[j],'This field is required');
		}
		if (x[j].className.indexOf('fieldEmail') > -1 && x[j].value.indexOf('@') == -1){
			writeError(x[j],'This is not a valid email address');
		}
	}
	if (!W3CDOM){
		alert(errorstring);
	}
	if (firstError){
		firstError.focus();
	}
	return validForm;
}

function writeError(obj,message) {
	validForm = false;
	if (obj.hasError){
		return;
	}
	if (W3CDOM){
		obj.className += ' error';
		obj.onchange = removeError;
		var sp = document.createElement('span');
		sp.className = 'error';
		sp.appendChild(document.createTextNode(message));
		obj.parentNode.appendChild(sp);
		obj.hasError = sp;
	}else{
		errorstring += obj.name + ': ' + message + '\n';
		obj.hasError = true;
	}
	if (!firstError){
		firstError = obj;
	}
}

function removeError(){
	this.className = this.className.substring(0,this.className.lastIndexOf(' '));
	this.parentNode.removeChild(this.hasError);
	this.hasError = null;
	this.onchange = null;
}