​x
 
<!DOCTYPE html> 
<html> 
<body> 
​
<video id="myVideo" width="640" height="360" controls>
  <source src="/i/video/shanghai.mp4" type="video/mp4">
  <source src="/i/video/shanghai.ogg" type="video/ogg">
  您的浏览器不支持 video 标签。
</video><br>
​
<button onclick="getPlaySpeed()" type="button">默认播放速度是多少？</button>
<button onclick="setPlaySpeed()" type="button">设置视频以慢动作播放</button>
​
<script>
var x = document.getElementById("myVideo");
​
function getPlaySpeed() { 
  alert(x.defaultPlaybackRate);
} 
​
function setPlaySpeed() { 
  x.defaultPlaybackRate = 0.5;
  x.load();
} 
</script> 
​
</body> 
</html>
​