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peerjs


			
				
					
						
						
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  <title>PeerJS Documentation</title>
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  <section class="start">
    <h1><a href="/">PeerJS</a> <span class="title">docs</span></h1>
    <p><br>PeerJS simplifies peer-to-peer data, video, and audio calls.</p>
      <p>This guide will show you the basic concepts of the PeerJS API. If
      you learn better from seeing a working app, <a href="/examples">see the examples</a> page.</P>
      <h2>Setup</h2>
      <h3>1. Include the Javascript client</h3>
      <p>Add the PeerJS client library to your webpage.</p>
      <pre>&lt;script src="http://cdn.peerjs.com/0.3/peer.min.js"&gt;&lt;/script&gt;</pre>
      <p>If you prefer, you can host it yourself: <a download
        href="http://cdn.peerjs.com/0.3/peer.js">peer.js</a> or <a download
      href="http://cdn.peerjs.com/0.3/peer.min.js">peer.min.js</a></p>
      <h3>2. Create the Peer object</h3>
      <p>The Peer object is where we create and receive connections.</p>
      <pre>var peer = new Peer({key: 'lwjd5qra8257b9'});</pre>
      <p>The 'key' we're passing in to the Peer constructor is a PeerServer
      cloud API key. You can use ours for now, but you should <a
      href="http://peerjs.com/peerserver">sign up for your own free key</a>.
    PeerJS uses PeerServer for session metadata and candidate signaling. You can
    also <a href="http://github.com/peers/peerjs-server">run your own PeerServer</a> if you don't like the cloud.</p>
      <p>We're now ready to start making connections!</p>

      <h2>Usage</h2>
      <p>Every Peer object is assigned a random, unique ID when it's created.</p>
      <pre>peer.on('open', function(id){
  console.log('My peer ID is: ' + id);
});</pre>
      <p>When we want to connect to another peer, we'll need to know their peer
      id. You're in charge of communicating the peer IDs between users of your
      site. Optionally, you can pass in your own IDs to the <a href="#peer"><code>Peer</code>
        constructor</a>.</p>

      <p>Read the <a href="#peer">Peer API reference</a> for complete
      information on its <a href="#peer-options">options</a>, methods, <a href="#peeron">events</a>, and <a
        href="#peeron-error">error handling</a>.</p>

      <h3>Data connections</h3>
      <p>Start a data connection by calling <code>peer.connect</code> with the peer ID of the
      destination peer. Anytime another peer attempts to connect to your peer
      ID, you'll receive a <code>connection</code> event. </p>
      <div class="two-col">
        <div class="col col-header">Start connection</div>
        <div class="col col-header">Receive connection</div>
        <div class="col"><pre>var conn = peer.connect('dest-peer-id');</pre></div>
        <div class="col"><pre>peer.on('connection', function(conn) { ... });</pre></div>
        <div class="clear"></div>
      </div>
      <p><code>peer.connect</code> and the callback of the
      <code>connection</code> event will both provide a
      <code>DataConnection</code> object. This object will allow you to send and receive data:</p>
      <pre>conn.on('open', function(){
  // Receive messages
  conn.on('data', function(data){
    console.log('Received', data);
  });

  // Send messages
  conn.send('Hello!');
});</pre>
      <p>Read the <a href="#dataconnection">DataConnection API reference</a> for complete details on its methods and events.</p>
      <h3>Video/audio calls</h3>
      <p>Call another peer by calling <code>peer.call</code> with the peer ID of the destination
      peer. When a peer calls you, the <code>call</code> event is emitted.</p>
      <p>Unlike data connections, when receiving a <code>call</code> event, the call must be answered or no connection is established.</p>
      <div class="two-col">
        <div class="col col-header">Start call</div>
        <div class="col col-header">Answer call</div>
        <div class="col"><pre>// Call a peer, providing our mediaStream
var call = peer.call('dest-peer-id',
  mediaStream);

</pre></div>
        <div class="col"><pre>peer.on('call', function(call){
  // Answer the call, providing our mediaStream
  call.answer(mediaStream);
});</pre></div>
        <div class="clear"></div>
      </div>
      <p>When calling or answering a call, a MediaStream should be provided. The
      MediaStream represents the local video (webcam) or audio stream and can be
      obtained with some (browser-specific) version of <a
        href="https://developer.mozilla.org/en-US/docs/Web/API/Navigator.getUserMedia"><code>navigator.getUserMedia</code></a>. When answering a
      call, the MediaStream is optional and if none is provided then a one-way
      call is established. Once the call is established, its <code>open</code> property is
      set to true.</p>
      <p><code>peer.call</code> and the callback of the <code>call</code> event
      provide a MediaConnection object. The MediaConnection object itself emits
      a <code>stream</code> event whose callback includes the video/audio stream of the other peer.</p>
      <pre>call.on('stream', function(stream){
  // `stream` is the MediaStream of the remote peer.
  // Here you'd add it to an HTML video/canvas element.
});</pre>
      <p>Read the <a href="#mediaconnection">MediaConnection API reference</a> for complete details on its methods and events.</p>

      <h2>Common questions</h2>

        <h3>What kind of data can I send?</h3>

        <p>PeerJS has the <a
          href="https://github.com/binaryjs/js-binarypack">BinaryPack</a>
        serialization format built-in. This means you can send any JSON type as
        well as binary Blobs and ArrayBuffers. Simply send arbitrary data and
        you'll get it out the
        other side:</p>
          <pre>
conn.send({
  strings: 'hi!',
  numbers: 150,
  arrays: [1,2,3],
  evenBinary: new Blob([1,2,3]),
  andMore: {bool: true}
});</pre>

        <h3>Are there any caveats?</h3>

          <p>A very low percentage of users are behind symmetric NATs. When two
          symmetric NAT users try to connect to each other, NAT traversal is
        impossible and no connection can be made. A workaround is to proxy
      through what is known as a TURN server. The PeerServer cloud service does
    not provide a TURN server. You'll have to find your own. You can pass a TURN
  server into the <code>Peer</code> object options. This will allow your PeerJS app to work seamlessly for this situation</p>

        <h3>What is the current state of browser compatibility?</h3>

          <p>We keep an frequently-updated catalogue of WebRTC compatibility
          information and caveats <a href="/status">here</a>.</p>

        <h3>What if my peer has not yet connected to the server when I attempt
          to connect to it?</h3>

          <p>When you try to connect to a peer, PeerServer will hold a
          connection offer for up to 5 seconds before rejecting it. This is useful if you want to reconnect to a peer as it disconnects and reconnects rapidly between web pages.</p>

        <h3>What about latency/bandwidth?</h3>

          <p>Data sent between the two peers do not touch any other servers, so the connection speed is limited only by the upload and download rates of the two peers. This also means you don't have the additional latency of an intermediary server.</p>
          <p>The latency to establish a connection can be split into two
          components:
          the brokering of data and the identification of clients. PeerJS has been
          designed to minimize the time you spend in these two areas. For
          brokering, data is sent through an XHR streaming request before a WebSocket
          connection is established, then through WebSockets. For client
          identification, we provide you the ability to pass in your own peer
          IDs, thus eliminating the RTT for retrieving an ID from the server.</p>

        <h3>More questions?</h3>
          <p><a
            href="https://groups.google.com/forum/?fromgroups#!forum/peerjs">Discuss
            PeerJS on our Google Group.</a><br><br></p>
  </section>

  <header class="left">
    <h2>API Reference<a class="hide icon">&laquo;</a><a class="show icon">&raquo;</a></h2>
  </header>
  <header class="right">
    <h2>Getting Started</h2>
  </header>

  <section class="api">
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  </section>

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