function checkEmail() {
	var emailToCheck;
	var emailChecker = /^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i;
	with(window.document.emailSubmit) {
		emailToCheck = emailAddress;
	}
	
	if (emailToCheck.value != '' && !isEmail(emailToCheck.value)) {
		alert('Invalid email address, please re-enter');
		emailToCheck.focus();
		return false;
	}
	else {
		return true;
	}
}

function isEmail(str) {
	return emailChecker.test(str);
}

function thisMovie(movieName) {
	 if (navigator.appName.indexOf("Microsoft") != -1) {
		 return window[movieName];
	 } 
	 else {
		 return document[movieName];
	 }
 }