youtube-music/src/plugins/synced-lyrics/renderer/utils.tsx

import { render } from 'solid-js/web';

import { LyricsRenderer, setIsVisible, setPlayerState } from './renderer';
import { VideoDetails } from '@/types/video-details';

export const selectors = {
  head: '#tabsContent > .tab-header:nth-of-type(2)',
  body: {
    tabRenderer: '#tab-renderer[page-type="MUSIC_PAGE_TYPE_TRACK_LYRICS"]',
    root: 'ytmusic-description-shelf-renderer',
  },
};

export const tabStates = {
  true: (data?: VideoDetails) => {
    setIsVisible(true);
    setPlayerState(data ?? null);

    const tabRenderer = document.querySelector<HTMLElement>(
      selectors.body.tabRenderer,
    );
    if (!tabRenderer) return;

    let container = document.querySelector('#synced-lyrics-container');
    if (container) return;

    container = Object.assign(document.createElement('div'), {
      id: 'synced-lyrics-container',
    });

    tabRenderer.appendChild(container);
    render(() => <LyricsRenderer />, container);
  },
  false: () => {
    setIsVisible(false);
  },
};