var _fields;
function clearField(field) 
{
        if (field.defaultValue == field.value) field.value = '';
        else if (field.value == '') field.value = field.defaultValue;
    }

function setItemsForValidation(fields) {
        _fields = fields;
}

function validateItems(sender, args) {
    var valid = true;
    for (var index in _fields) {
        var field = _fields[index];
        if (field.defaultValue == field.value) valid = false;
        if (field.value == '') valid = false;
    }
    args.IsValid = valid;
}