code: function d3_time_parseWeekday(date, string, i) {
    d3_time_weekdayRe.lastIndex = 0;
    var n = d3_time_weekdayRe.exec(string.substring(i, i + 10));
    return n ? i += n[0].length : -1;
  }
docs: Note: weekday is validated, but does not set the date.