Convert an XML Schema date string to a Javascript Date

Question

I couldn't find a good implementation of this on the internet, so I wrote one. Here's hoping this page becomes the first hit in Google. Enjoy!

/**
 * Return a Javascript Date for the given XML Schema date string.  Return
 * null if the date cannot be parsed.
 *
 * Does not know how to parse BC dates or AD dates < 100.
 *
 * Valid examples of input:
 * 2010-04-28T10:46:37.0123456789Z
 * 2010-04-28T10:46:37.37Z
 * 2010-04-28T10:46:37Z
 * 2010-04-28T10:46:37
 * 2010-04-28T10:46:37.012345+05:30
 * 2010-04-28T10:46:37.37-05:30
 * 1776-04-28T10:46:37+05:30
 * 0150-04-28T10:46:37-05:30
 */
var xmlDateToJavascriptDate = function(xmlDate) {
  // It's times like these you wish Javascript supported multiline regex specs
  var re = /^([0-9]{4,})-([0-9]{2})-([0-9]{2})T([0-9]{2}):([0-9]{2}):([0-9]{2})(\.[0-9]+)?(Z|([+-])([0-9]{2}):([0-9]{2}))?$/;
  var match = xmlDate.match(re);
  if (!match)
    return null;

  var all = match[0];
  var year = match[1];  var month = match[2];  var day = match[3];
  var hour = match[4];  var minute = match[5]; var second = match[6];
  var milli = match[7]; 
  var z_or_offset = match[8];  var offset_sign = match[9]; 
  var offset_hour = match[10]; var offset_minute = match[11];

  if (offset_sign) { // ended with +xx:xx or -xx:xx as opposed to Z or nothing
    var direction = (offset_sign == "+" ? 1 : -1);
    hour =   parseInt(hour)   + parseInt(offset_hour)   * direction;
    minute = parseInt(minute) + parseInt(offset_minute) * direction;
  }
  var utcDate = Date.UTC(year, month, day, hour, minute, second, (milli || 0));
  return new Date(utcDate);
}

Feel free to use, modify, and redistribute without credit.