// JavaScript Document

function validateForm(f) {
	var error = false;
	var name = f.txtName;
	var email = f.txtEmail;
	var subject = f.txtSubject;
	var message = f.txaMessage;	
	
	var emailLabel = document.getElementById("label4email");
	var subjectLabel = document.getElementById("label4subject");
		
	var emailFlag;
	
	if(email.value.length == 0) { // if email is not typed
		error = true;
		email.style.background = 'Yellow';	
		emailLabel.innerHTML = "<br/>Email address is required!";
		email.focus();
	} else {
		emailFlag = isEmail(email.value);
		if(emailFlag == true) {
			email.style.background = 'White';
			emailLabel.innerHTML = "";
		} else {
			error = true;
			emailLabel.innerHTML = "<br/>Email address is not valid!";
			email.style.background = 'Yellow';	
		}
	} // if(email.value.length == 0)

	if( (subject.value.length == 0) && (message.value.length == 0) ) { // Both of subject and message are empty
		error = true;
		subject.style.background = 'Yellow';	
		message.style.background = 'Yellow';	
		subjectLabel.innerHTML = "Please type subject or message!";
		subject.focus();
		message.focus();
	} else { 
		subject.style.background = 'White';		
		message.style.background = 'White';
		subjectLabel.innerHTML = "";
	} // if( (subject.value.length == 0) && (message.value.lenght == 0) )

	if(error == true) {
		return false;
	} // if(error == true)
} // validate(...)

function isEmail(address) {
	var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
	//var address = document.forms[form_id].elements[email].value;
	if(reg.test(address) == false) {
	  //alert('Invalid Email Address');
	  return false;
	} else {
		return true;   
	}
}