<div class="audio">
 <audio></audio>
 <div class="audio-controller">
 <span class="audio-prev"></span>
 <span class="audio-state"></span>
 <span class="audio-next"></span>
 </div>
 <div class="audio-bar">
 <span class="audio-time-current"></span>
 <div class="audio-progress">
  <div>
  <div></div>
  <div></div>
  </div>
  </div>
 <span class="audio-time-duration"></span>
 </div>
 <div class="audio-volume">
 <span class="audio-volume-icon"></span>
 <div class="audio-volume-adjust">
  <div>
  <div></div>
  <div></div>
  </div>
 </div>
 </div>
</div>

// 最外层作为进度条暗的长度区域
<div>
 // 最内层是实际表示进度
 <div></div>
</div>

 // 滑动效果
 bar.addEventListener('mousedown', function(e) {
 e.stopPropagation();
 // 获取滑块被选择时相对文档的初始X轴值
 options.clientX = e.clientX;
 // 偏移量
 options.left = this.offsetLeft;
 options.max = bgNode.offsetWidth - this.offsetWidth / 2;
 options.isDrag = true;
 });
 document.addEventListener('mousemove', function(e) {
 e.stopPropagation();
 if (options.isDrag) {
  let currentClientX = e.clientX,
  left = options.left,
  max = options.max,
  initClientX = options.clientX,
  barHalfWidth = bar.offsetWidth / 2,
  fgWidth = 0,
  // 设置要滑动到的位置点(x轴方向偏移量)
  to = Math.max(0, Math.min(max, left + (currentClientX - initClientX)));

  bar.style.left = to + 'px';
  if (to > barHalfWidth) {
  fgWidth = to + barHalfWidth;
  }
  fgNode.style.width = Math.max(0, fgWidth) + 'px';
  options.offsetX = Math.max(0, fgWidth);
 }
 });

 bgNode.parentNode.addEventListener('mouseup', function(e) {
 e.stopPropagation();
 if (options.isDrag) {
  // 绘制此时的进度
  tools.timeUpdateOrVolumeUpdate(options.offsetX, type);
  options.isDrag = false;
 }
 });