js屏幕录制

javascript

javascript屏幕录制

新版本浏览器支持js的屏幕录制功能，用到了navigator.mediaDevices.getDisplayMedia方法和MediaRecorder类。
demo:

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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>js屏幕录制</title>
</head>
<body>
  <div>
    <video class="video" width="600px" controls></video>
  </div>
  <div>
    <button class="record-btn">record</button>
    <button class="stop-btn" style="display: none;">stop</button>
  </div>
</body>
<script>
  let mediaRecorder, stream;
  let btnRecord = document.querySelector(".record-btn")
  let btnStop = document.querySelector(".stop-btn")
  
  btnRecord.addEventListener("click", async function () {
    btnStop.style.display = 'block';
    btnRecord.style.display = 'none';

    stream = await navigator.mediaDevices.getDisplayMedia({ 
      video: true
    }) 
    // 需要更好的浏览器支持 
    const mime = MediaRecorder.isTypeSupported("video/webm; codecs=vp9")  
               ? "video/webm; codecs=vp9" 
               : "video/webm"
    mediaRecorder = new MediaRecorder(stream, { 
        mimeType: mime 
    }) 
    
    let chunks = [] 
    mediaRecorder.addEventListener('dataavailable', function(e) { 
        chunks.push(e.data) 
    }) 
    
    mediaRecorder.addEventListener('stop', function(){ 
      let blob = new Blob(chunks, { 
          type: chunks[0].type 
      }) 
      let url = URL.createObjectURL(blob) 
  
      let video = document.querySelector("video") 
      video.src = url 
  
      let a = document.createElement('a') 
      a.href = url 
      a.download = 'video.webm'
      a.click()
    }) 
    // 必须手动启动 
    mediaRecorder.start() 
  })

  btnStop.addEventListener('click', function(evt) {
    btnStop.style.display = 'none';
    btnRecord.style.display = 'block';
    // 隐藏记录的图标
    stream.getTracks() // get all tracks from the MediaStream
    .forEach( track => track.stop() ); // stop each of them

    mediaRecorder.stop();
  }, false);
</script>
</html>

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