code: function normalizeIso8601TimeZone(value) {
      if (value === 'Z') {
        return 0;
      }
  
      var regex = /^([+-])(\d\d):?(\d\d)$/;
      var matches = regex.exec(value);
      if (matches === null) {
        return NaN;
      } else {
        var multiplicationFactor = (matches[1] === '+') ? 1 : -1;
        var hour = parseInt(matches[2], 10);
        var minute = parseInt(matches[3], 10);
  
        return multiplicationFactor * ((hour * 60) + minute);
      }
    }
docs: Converts an ISO 8601 time zone into the number of minutes offset from UTC