Calculating week numbers

JavaScript does not have a built-in function to calculate the ISO week number from a day. Therefore, to get the week number, in the ForNAV Designer, you must paste the following code into the OnPreReport trigger:

 

Date.prototype.getWeek = function() {

  var date = new Date(this.getTime());

  date.setHours(0, 0, 0, 0);

  // Thursday in current week decides the year.

  date.setDate(date.getDate() + 3 – (date.getDay() + 6) % 7);

  // January 4 is always in week 1.

  var week1 = new Date(date.getFullYear(), 0, 4);

  // Adjust to Thursday in week 1 and count number of weeks from date to week1.

  return 1 + Math.round(((date.getTime() – week1.getTime()) / 86400000

                        – 3 + (week1.getDay() + 6) % 7) / 7);

}

 

When the function is there, you can use it in JavaScript for code and source expressions.

 

For example: SalesHeader.LastShipmentDate.getWeek()