function isEmpty(str){
	return (str == null) || (str.length == 0);
}

function isEmail(str){
	var re = /^([_a-z0-9-]+(\.[_a-z0-9-]+)*)@([_a-z0-9-]+(\.[_a-z0-9-]+)*)\.([a-z]{2,6})$/i;
	if (re.test(str)) return true;
	return false;
}

function isAlpha(str){
	var re = /[^a-zA-Z]/
	if (re.test(str)) return false;
	return true;
}

function isNumeric(str){
	var re = /[^0-9]/
	if (re.test(str)) return false;
	return true;
}

function isAlphaNumeric(str){
	var re = /[^a-zA-Z0-9]/
	if (re.test(str)) return false;
	return true;
}

function isLength(str, len){
	return str.length == len;
}

function isLengthBetween(str, min, max){
	return (str.length >= min)&&(str.length <= max);
}

// returns true if the string is a US phone number formatted as...
// (000)000-0000, (000) 000-0000, 000-000-0000, 000 000 0000, 0000000000
function isPhoneNumber(str){
	var re = /^([(]{1}[0-9]{3}[)]{1}|[0-9]{3,3})[- ]{0,1}[0-9]{3}[- ]{0,1}[0-9]{4}$/;
	if (re.test(str)) return true;
	return false;
}

// returns true if the string is a valid date formatted as...
// yyyy mm dd, yyyy/mm/dd, yyyy.mm.dd, yyyy-mm-dd
function isDate(str){
	var re = /^(\d{4})[\s\.\/-](\d{1,2})[\s\.\/-](\d{1,2})$/
	if (!re.test(str)) return false;
	var result = str.match(re);
	var m = (result[2]);
	var d = (result[3]);
	var y = (result[1]);
	if(m < 1 || m > 12 || y < 1900 || y > 2100) return false;
	if(m == 2){
		var days = ((y % 4) == 0) ? 29 : 28;
	}
	else if(m == 4 || m == 6 || m == 9 || m == 11){
		var days = 30;
	}
	else{
		var days = 31;
	}
	return (d >= 1 && d <= days);
}

function isPostalCode(str){
	if(str.match(/^[a-zA-Z][0-9][a-zA-Z][0-9][a-zA-Z][0-9]$/)) {
		return true;
	}
	return false;
}

function isFloat(strString){
	var strValidChars = "0123456789.";
	var strChar;
	var blnResult = true;
	if (strString.length == 0) return true;
	if(strString.indexOf(".") != strString.lastIndexOf(".")) return false;
	for (i = 0; i < strString.length && blnResult == true; i++){
		strChar = strString.charAt(i);
		if (strValidChars.indexOf(strChar) == -1){
			blnResult = false;
		}
	}
	return blnResult;
}

function isInt(strString){
	var strValidChars = "0123456789";
	var strChar;
	var blnResult = true;
	if (strString.length == 0) return true;
	for (i = 0; i < strString.length && blnResult == true; i++){
		strChar = strString.charAt(i);
		if (strValidChars.indexOf(strChar) == -1){
			blnResult = false;
		}
	}
	return blnResult;
}