Get week of year in JavaScript like in PHP

Question

How do I get the current weeknumber of the year, like PHP\'s date(\'W\')?

It should be the ISO-8601 week number of year, weeks starting

Answer 1

I found useful the Java SE's SimpleDateFormat class described on Oracle's specification: http://goo.gl/7MbCh5. In my case in Google Apps Script it worked like this:

function getWeekNumber() {
  var weekNum = parseInt(Utilities.formatDate(new Date(), "GMT", "w"));
  Logger.log(weekNum);
}

For example in a spreadsheet macro you can retrieve the actual timezone of the file:

function getWeekNumber() {
  var weekNum = parseInt(Utilities.formatDate(new Date(), SpreadsheetApp.getActiveSpreadsheet().getSpreadsheetTimeZone(), "w"));
  Logger.log(weekNum);
}