Youtube format video duration

date-format.js

export function getVideoDurationString(iso8601DateString) {
  if (!iso8601DateString || iso8601DateString === '') {
    return '';
  }

  // new Date(Date.parse(...)) doesn't work here
  // therefore we are using our regex approach
  let {days, hours, minutes, seconds} = parseISO8601TimePattern(iso8601DateString);

  let secondsString = seconds.toString();
  let minutesString = minutes.toString();
  let accumulatedHours = days * 24 + hours;

  if (seconds < 10) {
    secondsString = seconds.toString().padStart(2, '0');
  }
  if (minutes < 10 && hours !== 0) {
    minutesString = minutesString.toString().padStart(2, '0');
  }
  if (!accumulatedHours) {
    return [minutesString, secondsString].join(':');
  } else {
    return [accumulatedHours, minutesString, secondsString].join(':');
  }
}