//validation functions.
var isString = function(_string)
{
    if (typeof(_string) == "string") return true; 
    else return false;
};

var isEmpty = function(_obj)
{
    if (_obj == null || typeof(_obj) == "undefined") return true; 
    else return false;
};

var isNumeric = function(_num)
{
    if (typeof(_num) == "number") return true;
    else return false;
};

var isEmptyString = function(_stringObj)
{
    while (_stringObj.parentNode.lastChild != _stringObj)
    {
        _stringObj.parentNode.removeChild(_stringObj.parentNode.lastChild);
    }    
    if (!isString(_stringObj.value) || _stringObj.value.length == 0)
    {
        _stringObj.style.backgroundColor = "#FFFF77";
        //_stringObj.parentNode.appendChild(document.createElement('br'));
        var errorMsgObj = document.createElement('font');
        errorMsgObj.setAttribute("color", "#FF0000");
        errorMsgObj.appendChild(document.createTextNode('*required'));
        _stringObj.parentNode.appendChild(errorMsgObj);
        return true;
    }
    else 
    {
        _stringObj.style.backgroundColor = "#FFFFFF";
        return false;
    }        
};

var isEmptySelect = function(_selectObj)
{
    while (_selectObj.parentNode.lastChild != _selectObj)
    {
        _selectObj.parentNode.removeChild(_selectObj.parentNode.lastChild);
    }
    var _selectedValue = _selectObj.options[_selectObj.selectedIndex].value;    
    if (_selectedValue == -1)
    {
        _selectObj.style.backgroundColor = "#FFFF77";
        //_selectObj.parentNode.appendChild(document.createElement('br'));
        var errorMsgObj = document.createElement('font');
        errorMsgObj.setAttribute("color", "#FF0000");
        errorMsgObj.appendChild(document.createTextNode('*required'));  
        _selectObj.parentNode.appendChild(errorMsgObj);      
        return true;
    }
    else 
    {
        _selectObj.style.backgroundColor = "#FFFFFF";
        return false;
    }        
};

var isValidEMail = function(_emailObj)
{
    while (_emailObj.parentNode.lastChild != _emailObj)
    {
        _emailObj.parentNode.removeChild(_emailObj.parentNode.lastChild);
    }    
    if (!isEmptyString(_emailObj))
    {
        var validEMail = /^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$/;
        if (!validEMail.test(_emailObj.value))
        {
            _emailObj.style.backgroundColor = "#FFFF77";
            //_emailObj.parentNode.appendChild(document.createElement('br'));
            var errorMsgObj = document.createElement('font');
            errorMsgObj.setAttribute("color", "#FF0000");
            errorMsgObj.appendChild(document.createTextNode('*invalid e-mail.'));
            _emailObj.parentNode.appendChild(errorMsgObj);
            return false;
        }
        _emailObj.style.backgroundColor = "#FFFFFF";
        return true;
    } else {
        _emailObj.style.backgroundColor = "#FFFF77";
        return false;
    }
};