function isBlank(str) {
	if (str == '') {
		alert('Please input something...');
		return false;
	}	
}

function matchEmail(str1, str2) {
	if (str1 == '') {
		alert('Please input your email address.');
		document.checkout.email1.focus();
		return false;
	}

	if (str2 == '') {
		alert('Please input your email address.');
		document.checkout.email2.focus();
		return false;
	}

	if (str1 != str2) {
		alert('Both email addresses don\'t match...');
		document.checkout.email1.value = '';
		document.checkout.email2.value = '';
		document.checkout.email1.focus();
		return false;
	}
}

function isAlphabet(str) {
	if (str == '') {
		alert('Please input something...');
		return false;
	}

	for (var i = 0; i < str.length; i++) {
		var alpha = str.charAt(i);
		var code = alpha.charCodeAt(0);

		if ((code > 64 && code < 91) || (code > 96 && code < 123) || (code == 32)) {
			
		} else {
			alert('Please input alphabet and white space only.');
			return false;
		}
	}
}

function isAlphanumeric(str) {
	if (str == '') {
		alert('Please input something...');
		return false;
	}

	for (var i = 0; i < str.length; i++) {
		var alpha = str.charAt(i);
		var code = alpha.charCodeAt(0);

		if ((code > 64 && code < 91) || (code > 96 && code < 123) || (code > 47 && code < 58) || (code == 95)) {
		
		} else if (code == 32) {
			alert('Whitespace is not allowed.');
			return false;
		} else {
			alert('Please input alphabet and numeric only.');
			return false;
		}
	}
}

function isEmail(str) {
	if (str == '') {
		alert('Please input something...');
		return false;
	}

	var at = '@';
	var dot = '.';
	var lat = str.indexOf(at);
	var lstr = str.length;
	var ldot = str.indexOf(dot);
	
	if (str.indexOf(at) == -1) {
		alert('Invalid Email Address.');
		return false;
	}

	if (str.indexOf(at) == -1 || str.indexOf(at) == 0 || str.indexOf(at) == lstr) {
		alert('Invalid Email Address.');
		return false;
	}

	if (str.indexOf(dot) == -1 || str.indexOf(dot) == 0 || str.indexOf(dot) == lstr) {
		alert('Invalid Email Address.');
		return false;
	}

	if (str.indexOf(at, (lat + 1)) != -1) {
		alert('Invalid Email Address.');
		return false;
	}

	if (str.substring(lat - 1, lat) == dot || str.substring(lat + 1, lat + 2) == dot) {
		alert('Invalid Email Address.');
		return false;
	}

	if (str.indexOf(dot, (lat + 2)) == -1) {
		alert('Invalid Email Address.');
		return false;
	}
	
	if (str.indexOf(" ") != -1) {
		alert('Invalid Email Address.');
		return false;
	}

	return true;
}