function checkform(fields) {
    var errFields = new Array();
    for (var i = 0; i < fields.length; i += 2) {
	if (fields[i] == "")
	    errFields[errFields.length] = fields[i + 1];
    }
    if (errFields.length == 0) return true;
    else {
	var text = errFields.length == 1 ? "Das Feld " : "Die Felder ";
	for (var i = 0; i < errFields.length; i++) {
	    text += errFields[i];
	    if (errFields.length > 1) {
		if (i == errFields.length - 2) text += " und ";
		else if (i < errFields.length - 2) text += ", ";
	    }
	}
	text += errFields.length == 1 ? " darf" : " dürfen";
	text += " nicht leer sein!";
	alert(text);
	return false;
    }
}