compute the sum of a YouTube videos playlist

sum_youtube_videos_durations.js

// a JS script to compute the sum of a YouTube videos playlist

function unify_format(duration) {
    // sum_durations assumes the format 'h:m:s' which is not the case for videos less than an hour
    // this function will append missing values to fit into the expected format.
    // count number of ':' in duration
    const count = duration.split(":").length - 1;
    if (count == 0) // e.g. '27'
      return `0:0:${duration}`;
    if (count == 1) // e.g. '2:27'
      return `0:${duration}`;
    // count == 2 // e.g. '1:2:27'
    return duration;
}

function sum_durations(durations) {
  let total_seconds = 0;

  for (let duration of durations) {
    duration = unify_format(duration);
    const [hours, minutes, seconds] = duration.split(":").map(part => parseInt(part));
    total_seconds += hours * 3600 + minutes * 60 + seconds;
  }

  const total_hours = Math.floor(total_seconds / 3600);
  const remaining_minutes = Math.floor((total_seconds % 3600) / 60);
  const remaining_seconds = total_seconds % 60;

  return `${total_hours}:${remaining_minutes}:${remaining_seconds}`;
}

let durations = [...document.querySelectorAll('.playlist-items span.ytd-thumbnail-overlay-time-status-renderer')].map(x => x.innerText.trim());
console.log(`playlist total length: ${sum_durations(durations)}`);