function checkAndUpdateField(idStr, type)
{
	var result = true;

	var elem = document.getElementById(idStr);
	var value = (elem ? elem.value : null);

	if (value == null) return false;

	if (type == "stext")
	{
		result = value.match("^\\D+$") != null;
	} else if (type == "sdtext") {
		result = value.match("^.+$") != null;
	} else if (type == "number") {
		result = value.match("^\\d+$") != null;
	} else if (type == "email") {
		result = value.match("^(.*)@(.*)\\.(.*)$") != null;
	} else {
		// do nothing
	}

	var elem = document.getElementById(idStr + "_err");
	if (elem)
	{
		elem.style.display = (result ? "none" : "block");
	}

	return result;
}