function validateNonEmpty(inputField, helpText) {
	// See if the input value contains any text
    if (inputField.value.length == 0) {
    	if(helpText != null)
			helpText.innerHTML = "Please enter a value.";
		
		inputField.focus();
		
		return false;
	}
	else {
		if(helpText != null)
			helpText.innerHTML = "";
	}
	return true;
}
	  
function validateLength(minLength, maxLength, inputField, helpText) {
	if(inputField.value.length < minLength || inputField.value.length > maxLength)
	{
		if(helpText != null)
			helpText.innerHTML = "The message you entered is either too short or too long. Please re-enter.";
		
		inputField.focus();
		
		return false;
	}
	else {
		if(helpText != null)
			helpText.innerHTML = "";
	}
	
	return true;
}
	  
// generic regular expression validation function
function validateRegEx(regex, inputStr, helpText, helpMessage) {
	// see if the inputStr data validates OK
	if(!regex.test(inputStr)) {
		if(helpText != null)
			helpText.innerHTML = helpMessage;
			
		return false;
	}
	else {
		if(helpText != null)
			helpText.innerHTML = "";
		return true;			
	}
}
	  
function validateZipCode(inputField, helpText) {
	if(inputField.value.length != 5) {
		// the data is invalid, so set the help message
		if(helpText != null)
			helpText.innerHTML = "Please enter exactly five digits.";
			
		inputField.focus();
		
		return false;
	}
	else 
		return validateRegEx(/^\d{5}$/, inputField.value, helpText, "Please enter a number.");
}
	  
function validateDate(inputField, helpText) {
	if(!validateNonEmpty(inputField, helpText))
		return false;
		
	if(!validateRegEx(/^\d{2}\/\d{2}\/(\d{2}|\d{4})$/, inputField.value, helpText, "Please enter a date in the form MM/DD/YYYY.")) {
		inputField.focus();
		return false;
	}
	
	return true;
}
	  
function validatePhone(inputField, helpText) {
	if(!validateNonEmpty(inputField, helpText))
		return false;
	
	if(!validateRegEx(/^\d{3}-\d{3}-\d{4}$/, inputField.value, helpText, "Please enter a phone number in the form ###-###-####.")) {
		inputField.focus();
		return false;
	}
	
	return true;
}
	
function validateEmail(inputField, helpText) { 
	if(!validateNonEmpty(inputField, helpText))
		return false;
	
	if(!validateRegEx(/^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/, inputField.value, helpText, "Please enter a valid email address.")) {
		inputField.focus();
		return false;
	}
	
	return true;
}