getISOTimestamp.js

pad = (num) => {
  return num < 10 ? `0${num}` : num.toString();
};
getIsoDate = (date) => {
  const year = date.getFullYear();
  const month = pad(date.getMonth() + 1);
  const monthDay = pad(date.getDate());
  return `${year}-${month}-${monthDay}`;
};
getIsoTime = (date) => {
  const hours = pad(date.getHours());
  const minutes = pad(date.getMinutes());
  const seconds = pad(date.getSeconds());
  const milliseconds = pad(date.getMilliseconds());
  return `${hours}:${minutes}:${seconds}.${milliseconds}`;
};
getIsoOffset = (date) => {
  const offset = date.getTimezoneOffset();
  if (offset === 0) {
    return 'Z';
  }
  const absOffset = Math.abs(offset);
  const offsetHours = pad(absOffset / 60);
  const offsetMinutes = pad(absOffset % 60);
  const offsetSign = offset > 0 ? '-' : '+';
  return `${offsetSign}${offsetHours}:${offsetMinutes}`;
};
getTimestamp = () => {
  const date = new Date();
  const isoDate = getIsoDate(date);
  const isoTime = getIsoTime(date);
  const isoOffset = getIsoOffset(date);
  return `${isoDate}T${isoTime}${isoOffset}`;
};
getTimestamp()