lib/date.js
function setISOWeekNumber(d, num) {
  if (isNumber(num)) {
    // Intentionally avoiding updateDate here to prevent circular dependencies.
    var isoWeek = cloneDate(d), dow = getWeekday(d);
    moveToFirstDayOfWeekYear(isoWeek, ISO_FIRST_DAY_OF_WEEK, ISO_FIRST_DAY_OF_WEEK_YEAR);
    setDate(isoWeek, getDate(isoWeek) + 7 * (num - 1));
    setYear(d, getYear(isoWeek));
    setMonth(d, getMonth(isoWeek));
    setDate(d, getDate(isoWeek));
    setWeekday(d, dow || 7);
  }
  return d.getTime();
}
function setISOWeekNumber(d, num) {
  if (isNumber(num)) {
    // Intentionally avoiding updateDate here to prevent circular dependencies.
    var isoWeek = cloneDate(d), dow = getWeekday(d);
    moveToFirstDayOfWeekYear(isoWeek, ISO_FIRST_DAY_OF_WEEK, ISO_FIRST_DAY_OF_WEEK_YEAR);
    setDate(isoWeek, getDate(isoWeek) + 7 * (num - 1));
    setYear(d, getYear(isoWeek));
    setMonth(d, getMonth(isoWeek));
    setDate(d, getDate(isoWeek));
    setWeekday(d, dow || 7);
  }
  return d.getTime();
}
function setISOWeekNumber ( d , num ) { if ( isNumber ( num ) ) { // Intentionally avoiding updateDate here to prevent circular dependencies. var isoWeek = cloneDate ( d ) , dow = getWeekday ( d ) ; moveToFirstDayOfWeekYear ( isoWeek , ISO_FIRST_DAY_OF_WEEK , ISO_FIRST_DAY_OF_WEEK_YEAR ) ; setDate ( isoWeek , getDate ( isoWeek ) + 7 * ( num - 1 ) ) ; setYear ( d , getYear ( isoWeek ) ) ; setMonth ( d , getMonth ( isoWeek ) ) ; setDate ( d , getDate ( isoWeek ) ) ; setWeekday ( d , dow || 7 ) ; } return d . getTime ( ) ; }
Week number helpers
Week number helpers