JavaScript奇淫技巧：20行代码，实现屏幕录像

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');

a.href = url;

a.download = 'video.webm';

a.click();

})

//手动启动

mediaRecorder.start()

});