Ermittelt die Kalenderwoche zum aktuellem Datum

Kalenderwoche.js

  function GetCurrentWeek() {
      let date = new Date();
      let currentThursday = new Date(date.getTime() + (3 - ((date.getDay() + 6) % 7)) * 86400000);
      let yearOfThursday = currentThursday.getFullYear();
      let firstThursday = new Date(new Date(yearOfThursday, 0, 4).getTime() + (3 - ((new Date(yearOfThursday, 0, 4).getDay() + 6) % 7)) * 86400000);
      let weekNumber = Math.floor(1 + 0.5 + (currentThursday.getTime() - firstThursday.getTime()) / 86400000 / 7);
      return weekNumber;
  }

  function donnerstag(datum) {
      var Do = new Date();
      Do.setTime(datum.getTime() + (3 - ((datum.getDay() + 6) % 7)) * 86400000);
      return Do;
  }


function GetCurrentKalenderwoche() {
    let Datum = new Date();
    let DoDat = donnerstag(Datum);
    let kwjahr = DoDat.getFullYear();
    let DoKW1 = donnerstag(new Date(kwjahr, 0, 4));
    let kw = Math.floor(1.5 + (DoDat.getTime() - DoKW1.getTime()) / 86400000 / 7);
    return kw;
}