Output total time of a playlist

youtube-playlist-total-time.js

/*
Note: This works for URLs like the following:
https://www.youtube.com/playlist?list=PLDV1Zeh2NRsAsbafOroUBnNV8fhZa7P4u
https://www.youtube.com/watch?v=oQQO_n57SB0&list=PLDV1Zeh2NRsAsbafOroUBnNV8fhZa7P4u&index=6
*/

const extra = window.location.pathname === "/watch" ? "panel-" : "";
const tag = `ytd-playlist-${extra}video-renderer`;
const playlistPanel = Array.from(document.getElementsByTagName(tag));
  
const timeStrings = playlistPanel.map((video) => {
    const timestamp = video.getElementsByTagName("ytd-thumbnail-overlay-time-status-renderer")[0];
    const value = timestamp.children[1].innerText;
    return value;
});

const timeInSeconds = timeStrings.reduce((total, curr) => {
    const [minutes, seconds] = curr.split(":");
    return parseInt(minutes * 60) + parseInt(seconds) + total;
}, 0);

console.log("Time in seconds:", timeInSeconds);
console.log(`${Math.round(timeInSeconds / 3600)}h ${Math.round(timeInSeconds / 60) % 60}m ${timeInSeconds % 60}s`);