用js帮我写一个视频播放倍速加上静音

Sure, here is some sample code in JavaScript to help you out:

// Get the video element and set its playback rate to 2x
var video = document.getElementsByTagName('video')[0];
video.playbackRate = 2;

// Mute the video
video.muted = true;

Please note that this code may need to be modified to fit the specific video player you are using.