function formatDate(datum, uhrzeit) {

    if(!datum) datum = new Date();

    var y = getFullYear(datum);
    var m = datum.getMonth();m++;
    var d = datum.getDate();

    var uhr = "";
    if(uhrzeit)
    {
       var x = '00' + datum.getHours();
       uhr += ' [' + x.substring( x.length - 2);
       x = '00' + datum.getMinutes();
       uhr += ':' + x.substring(  x.length - 2) + ']';
    }
    var wd = (new Array( 'So', 'Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa'))[datum.getDay()]
    return (wd + ' ' + d +"." + m + "." + y + uhr);
}




function dif(f)
{

     var d1 = string2date(f.a19_Dauer_Absicherung_Datum_von.value);
     var d2 = string2date(f.a20_Dauer_Absicherung_Datum_bis.value);
     Fehler=0;

var Aufschlag;

     if(!d1) d1 = new Date();
     if(!d2) d2 = new Date();



     if(d1 && d2)
     {
}}

function string2date(string)
{
    if(!string) return null;
    string += '';
    string = string.replace(/[-\/]/g, '.'); // Trennzeichen normalisieren
    string = string.replace(/[^0-9.: ]/g, ''); // ung?ltige Zeichen entfernen
    string = string.replace(/ +/g, ' '); // doppelte Leerzeichen entfernen
    var uhr = string.split(" "); // Uhrzeit abtrennen
    var split = uhr[0].split(".");
    var day = parseInt(split[0], 10);
    var month = parseInt(split[1] || 0, 10);
    var year = parseInt(split[2] || 0, 10);

    if(isNaN(year)) year = getFullYear();

    var check = new Date(year, month - 1, day);
    if(uhr[1])
    {
         var uhr = uhr[1].split(':');
         check.setHours( uhr[0] || 0 );
         check.setMinutes( uhr[1] || 0 );
         check.setSeconds( uhr[2] || 0 );
    }

    var day2 = check.getDate();
    var year2 = getFullYear(check);
    var month2 = check.getMonth() + 1;

    return ( year2 == year && month == month2 && day == day2 ) ? check
    : null;
}
function getFullYear(date)
{
    if(!date) date = new Date();
    if(typeof date.getFullYear != 'undefined') return date.getFullYear();
    var year = date.getYear();
    if(year < 1000) year += 2000;
    return year;
}