var hasSpamField = false;
var spamField = null;
var spamFieldText = null;
var spamFieldResult = null;

function checkSpamField(){
    if(hasSpamField && spamField!=null && spamFieldText!=null && spamFieldResult!=null){
        if(spamField.value != spamFieldResult){
            alert('Bitte "'+spamFieldText+'" beantworten.');
            spamField.focus();
            return false;
        }
    }
    return true;
}
function registerSpamField(field, text, result){
    hasSpamField = true;
    spamField = field;
    spamFieldText = text;
    spamFieldResult = result;
}