JS 实现录屏

var body = document.body;
body.addEventListener("click",async function(){
  var stream = await navigator.mediaDevices.getDisplayMedia({video: true});
  var mime = MediaRecorder.isTypeSupported("video/webm; codecs=vp9") ?"video/webm; codecs=vp9" :"video/webm";
  var mediaRecorder = new MediaRecorder(stream, {mimeType: mime});
  //录制
  var chunks = [];
  mediaRecorder.addEventListener('dataavailable', function(e) {
    chunks.push(e.data)
  })
  //停止
  mediaRecorder.addEventListener('stop', function(){
    var blob = new Blob(chunks, {type: chunks[0].type});
    var url = URL.createObjectURL(blob);
    var a = document.createElement('a');
    console.log( chunks[0])
    console.log( chunks)
    a.href = url;
    a.download = 'video.webm';
    a.click();
  })
  //手动启动
  mediaRecorder.start()
});