取消静音youtube视频引导程序

Question

当页面加载时，YouTube视频应播放没有声音的视频（取消静音），但我找不到合适的方法来解决此问题。

＆＃13;

＆＃13;

var video = document.getElementsByClassName("embed-responsive-item");
if(video == video.mute()){
	video == video.unmute();	
} else {
	video == video.unmute();
}

＆＃13;

<div class="embed-responsive embed-responsive-16by9">
<iframe class="embed-responsive-item" src="https://www.youtube.com/embed/KKp9g8fTBDQ?autoplay=1"></iframe>
  </div>

＆＃13;

＆＃13;

＆＃13;