Method updatePlayButton

js/ReadingSystem.js:624–632

* 更新播放按钮状态

()

   * 更新播放按钮状态
   */
  updatePlayButton() {
    if (!this.dom.playPauseBtn || !this.dom.audioPlayer) return;

    toggleClass(
      this.dom.playPauseBtn,
      'playing',
      !this.dom.audioPlayer.paused
    );
  }

  /**
   * 设置播放按钮禁用状态