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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              <div class="container">
    <video id="local" autoplay></video>
    <video id="remote" autoplay></video>
    <div class="action">
        <button id="getMediaBtn">Get user media</button>
        <button id="connectBtn" disabled>RTCPeerConnection</button>
        <button id="closeBtn" disabled>Close connection</button>
    </div>
</div>
            
          
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              .container {
    margin: 0 auto;
    max-width: 1000px;
}

video {
    width: 45%;
    background-color: #000;
    margin-bottom: 20px;
}

video#local {
    margin-right: 20px;
}

button {
    color: #fff;
    background-color: #52c41a;
    border: 1px solid #52c41a;
    border-radius: 4px;
    padding: 0 15px;
    height: 32px;
    cursor: pointer;
    transition: all .3s cubic-bezier(.645, .045, .355, 1);
}

button:hover {
    background-color: #73d13d;
    border-color: #73d13d;
}

button:not(:last-child) {
    margin-right: 20px;
}

button[disabled] {
    color: rgba(0, 0, 0, 0.25);
    background-color: #f5f5f5;
    border-color: #d9d9d9;
    cursor: not-allowed;
}

button[disabled]:hover {
    color: rgba(0, 0, 0, 0.25);
    background-color: #f5f5f5;
}
            
          
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              const localVideo = document.querySelector('#local');
const remoteVideo = document.querySelector('#remote');
const getMediaBtn = document.querySelector('#getMediaBtn');
const connectBtn = document.querySelector('#connectBtn');
const closeBtn = document.querySelector('#closeBtn');

let pc1, pc2, localStream;

getMediaBtn.addEventListener('click', getLocalStream);
connectBtn.addEventListener('click', createConnection);
closeBtn.addEventListener('click', close);

function getLocalStream() {
  console.log('获取本地媒体流');
  getMediaBtn.disabled = true;
  navigator.getUserMedia({
    video: true,
  }, function(stream) {
    localStream = stream;
    localVideo.srcObject = stream;
    connectBtn.disabled = false;
  }, function(err) {
    console.error(`getUserMedia() error: ${err.name}`);
  });
}

async function createConnection() {
  connectBtn.disabled = true;
  closeBtn.disabled = false;
  console.log('开始连接连接');

  pc1 = new RTCPeerConnection({});
  console.log('创建本地 pc 实例 pc1');
  pc1.addEventListener('icecandidate', e => onIceCandidate(pc2, e));

  pc2 = new RTCPeerConnection({});
  console.log('创建远程 pc 实例 pc2');
  pc2.addEventListener('icecandidate', e => onIceCandidate(pc1, e));
  pc2.addEventListener('addstream', gotRemoteStream);

  console.log('添加本地流到 pc1 中');
  pc1.addStream(localStream);

  console.log('pc1 创建 offer');
  const offer = await pc1.createOffer({
    offerToReceiveVideo: 1,
  });
  console.log(`Offer \n${offer.sdp}`);
  console.log('pc1 setLocalDescription');
  await pc1.setLocalDescription(offer);

  console.log('pc2 setRemoteDescription'); // 省去了发送 offer 信令给 pc2 的过程
  await pc2.setRemoteDescription(offer);
  console.log('pc2 createAnswer');
  const answer = await pc2.createAnswer();
  console.log(`Answer :\n${answer.sdp}`);
  console.log('pc2 setLocalDescription');
  await pc2.setLocalDescription(answer);

  console.log('pc1 setRemoteDescription'); // 省去了 pc2 将 answer 发送给 pc1 的过程
  await pc1.setRemoteDescription(answer);
}

function close() {
  console.log('关闭连接');
  pc1.close();
  pc2.close();
  pc1 = null;
  pc2 = null;
  closeBtn.disabled = true;
  connectBtn.disabled = false;
}

// 远程 pc2 实例获取到本地流
function gotRemoteStream(e) {
  if (remoteVideo.srcObject !== e.stream) {
    remoteVideo.srcObject = e.stream;
    console.log('pc2 收到媒体流');
  }
}

function getName(pc) {
  return (pc === pc1) ? 'pc1' : 'pc2';
}

// ICE 候选可用
async function onIceCandidate(pc, event) {
  await pc.addIceCandidate(event.candidate);
  console.log(`${getName(pc)} 添加 ICE candidate 候选成功:\n${event.candidate ? event.candidate.candidate : '(null)'}`);
}
            
          
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