Prints Week number from date in Google Sheets

weeknumber.gs

function printWeek() {
  var settings = SpreadsheetApp.getActive().getSheetByName('settings');
  var sheet = SpreadsheetApp.getActive().getSheetByName('test');
  const DATE = 0;
  const WEEK = 1;
  const START_ROW = 2;  // First row of data to process
  // Fetch settings:
  var config = settings.getRange(2,1,10,2).getValues(); // change range dependign on need
  var numRows = config[0][1];   // Number of rows to process
  if (typeof(numRows) !== 'number') {
    Logger.log("Problem getting settings!");
    return false;
  }
  // Fetch data:
  var dataRange = sheet.getRange(START_ROW, 1, numRows, 2);
  var data = dataRange.getValues();

  for (row = 0; row < numRows; row++) {
    if (typeof(data[row][WEEK]) === 'number') { // While week number is defined
      var wk = data[row][WEEK];
      var dt = data[row][DATE];
      if (dt instanceof Date) {
        dt = dt.yyyymmdd()
      }
      var sundayThatWeek = getDateOfNextWN(wk, 6).yyyymmdd();
      if (dt !== sundayThatWeek) {
        Logger.log("The date of week " + wk + " was changed from " + dt + " to " + sundayThatWeek);
        sheet.getRange(START_ROW + row, WEEK).setValue(sundayThatWeek);
        SpreadsheetApp.flush();
      }
    } else {
      Logger.log("The type of the week field was " + typeof(data[row][WEEK]));
      break;
    }
  }
  
};