// How To: array('onKeyUp' => "return imposeMaxLength(this, 500);", 'onKeyDown' => "return imposeMaxLength(this, 500);")
function imposeMaxLength(Object, MaxLen)	/* For textarea */
{
	if( Object.value.length <= MaxLen )
		return true;
	Object.value = Object.value.substring(0, MaxLen);
	return false;
}