webvideo-transcript-summary-core/src/video-types/youtube/url.ts

import { InvalidVideoIdError } from './errors';

const STANDARD_YOUTUBE_VIDEO_ID_LENGTH = 11 as const;

export const RE_YOUTUBE = /^.*(?:(?:youtu\.be\/|v\/|vi\/|u\/\w\/|embed\/)|(?:(?:watch)?\?v?:i?=|&v?:i?=))([^#&?]*).*/im;

export const retrieveVideoId = (videoId: string): string => {
  if (typeof (videoId as unknown) !== 'string') {
    throw new InvalidVideoIdError('The video ID must be a string.');
  }
  if (videoId.length === STANDARD_YOUTUBE_VIDEO_ID_LENGTH) {
    return videoId;
  }
  const matchId = videoId.match(RE_YOUTUBE);
  if (matchId && matchId.length > 1) {
    return matchId[1];
  }
  throw new InvalidVideoIdError('Impossible to retrieve Youtube video ID.');
};