learn-webrtc/auto.html at main · arifulislamat/learn-webrtc · GitHub

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<!doctype html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>WebRTC Auto-Signaling — Peer-to-Peer Chat</title>
    <style>
      *,
      *::before,
      *::after {
        box-sizing: border-box;
      }
      body {
        font-family:
          -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
          Arial, sans-serif;
        max-width: 720px;
        margin: 0 auto;
        padding: 24px 20px;
        color: #1a1a2e;
        background: #fafbfc;
        line-height: 1.5;
      }
      h1 {
        margin: 0 0 4px;
        font-size: 1.6rem;
      }
      h3 {
        font-size: 1rem;
        color: #24292f;
      }
      .subtitle {
        color: #666;
        font-size: 0.9rem;
        margin: 0 0 16px;
      }
      textarea {
        width: 100%;
        height: 40px;
        margin: 6px 0;
        padding: 10px;
        font-family:
          -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
        font-size: 0.9rem;
        border: 1px solid #d0d7de;
        border-radius: 6px;
        resize: vertical;
        transition: border-color 0.15s;
      }
      textarea:focus {
        outline: none;
        border-color: #0969da;
        box-shadow: 0 0 0 3px rgba(9, 105, 218, 0.15);
      }
      button {
        padding: 8px 18px;
        margin: 6px 4px 6px 0;
        cursor: pointer;
        border: 1px solid #d0d7de;
        border-radius: 6px;
        background: #f6f8fa;
        font-size: 0.85rem;
        font-weight: 500;
        transition: all 0.15s;
      }
      button:hover:not(:disabled) {
        background: #0969da;
        color: #fff;
        border-color: #0969da;
      }
      #status {
        padding: 10px 14px;
        background: #ddf4ff;
        border: 1px solid #54aeff44;
        border-radius: 6px;
        margin: 12px 0;
        font-size: 0.88rem;
        font-weight: 500;
      }
      #log {
        font-family: "SF Mono", "Fira Code", "Cascadia Code", monospace;
        font-size: 12px;
        background: #24292f;
        color: #7ee787;
        padding: 16px;
        border-radius: 8px;
        min-height: 150px;
        max-height: 300px;
        overflow-y: auto;
        white-space: pre-wrap;
        line-height: 1.6;
      }
      #chatSection {
        display: none;
      }
      #receivedMessages {
        border: 1px solid #d0d7de;
        border-radius: 6px;
        padding: 12px;
        min-height: 100px;
        max-height: 300px;
        overflow-y: auto;
        background: #fff;
        margin-bottom: 10px;
      }
      #receivedMessages p {
        margin: 3px 0;
        font-size: 0.9rem;
      }
      .sent {
        color: #0550ae;
      }
      .received {
        color: #1a7f37;
      }
      .info {
        border: 1px solid #54aeff44;
        background: #ddf4ff;
        padding: 14px 18px;
        border-radius: 8px;
        margin: 12px 0;
        font-size: 0.88rem;
        color: #24292f;
      }
      .info code {
        background: #afdbf544;
        padding: 2px 6px;
        border-radius: 4px;
        font-size: 0.85em;
      }
      footer {
        margin-top: 32px;
        padding-top: 16px;
        border-top: 1px solid #d8dee4;
        text-align: center;
        font-size: 0.82rem;
        color: #656d76;
      }
      footer a {
        color: #0969da;
        text-decoration: none;
      }
      footer a:hover {
        text-decoration: underline;
      }
    </style>
  </head>
  <body>
    <h1>WebRTC with Auto-Signaling</h1>
    <p class="subtitle">
      WebSocket-based signaling — open in two tabs to connect automatically
    </p>

    <div class="info">
      <strong>How to use:</strong> Open this page in <b>two tabs</b>. The first
      tab becomes the <em>Sender</em> (creates the offer), and the second tab
      becomes the <em>Receiver</em> (answers it). The signaling server
      (<code>server.js</code>) relays the offer/answer/ICE candidates
      automatically.
    </div>

    <div id="status">Status: Connecting to signaling server...</div>

    <div id="chatSection">
      <h3>Chat (peer-to-peer via Data Channel)</h3>
      <div id="receivedMessages"></div>
      <textarea id="messageInput" placeholder="Type your message..."></textarea>
      <button id="sendMessageButton">Send Message</button>
    </div>

    <h3>Signaling Log</h3>
    <div id="log"></div>

    <script>
      // ========== DOM ==========
      const statusDiv = document.getElementById("status");
      const logDiv = document.getElementById("log");
      const chatSection = document.getElementById("chatSection");
      const messageInput = document.getElementById("messageInput");
      const receivedMessagesDiv = document.getElementById("receivedMessages");
      const sendButton = document.getElementById("sendMessageButton");

      let pc; // RTCPeerConnection
      let dataChannel; // Data channel for chat
      let ws; // WebSocket to signaling server
      let isSender = false;

      function setStatus(msg) {
        statusDiv.textContent = "Status: " + msg;
      }

      function log(msg) {
        const time = new Date().toLocaleTimeString();
        logDiv.textContent += `[${time}] ${msg}\n`;
        logDiv.scrollTop = logDiv.scrollHeight;
        console.log(msg);
      }

      // ========== 1. Connect to Signaling Server ==========
      ws = new WebSocket(`ws://${location.host}`);

      ws.onopen = () => {
        log("Connected to signaling server");
        setStatus("Connected to signaling server. Waiting for peer...");
        // Tell the server we're here; first client to connect becomes the sender
        ws.send(JSON.stringify({ type: "join" }));
      };

      ws.onmessage = async (event) => {
        const msg = JSON.parse(event.data);
        log(`Received signaling message: ${msg.type}`);

        switch (msg.type) {
          // ---- Another peer joined, we are the sender ----
          case "join":
            isSender = true;
            log("Another peer joined — I am the SENDER. Creating offer...");
            await startAsSender();
            break;

          // ---- Received an offer, we are the receiver ----
          case "offer":
            log("Received offer — I am the RECEIVER. Creating answer...");
            await startAsReceiver(msg);
            break;

          // ---- Received an answer (we are the sender) ----
          case "answer":
            log("Received answer. Setting remote description...");
            await pc.setRemoteDescription(new RTCSessionDescription(msg));
            break;

          // ---- Received an ICE candidate ----
          case "ice-candidate":
            if (pc) {
              try {
                log("Adding remote ICE candidate");
                await pc.addIceCandidate(msg.candidate);
              } catch (err) {
                log("ICE candidate error (ignored): " + err.message);
              }
            }
            break;
        }
      };

      ws.onerror = (err) => {
        setStatus("WebSocket error — is server.js running?");
        log("WebSocket error: " + err.message);
      };

      // ========== 2. Create Peer Connection ==========
      function createPeerConnection() {
        pc = new RTCPeerConnection({
          iceServers: [
            { urls: "stun:stun.l.google.com:19302" },
            { urls: "stun:stun1.l.google.com:19302" },
            { urls: "stun:stun2.l.google.com:19302" },
            { urls: "stun:stun3.l.google.com:19302" },
            { urls: "stun:stun4.l.google.com:19302" },
          ],
          // Allow all candidate types for best LAN connectivity
          iceCandidatePoolSize: 2,
        });

        // Trickle ICE: send each candidate to the other peer as it's discovered
        pc.onicecandidate = (event) => {
          if (event.candidate && event.candidate.candidate) {
            log("Sending ICE candidate to peer");
            ws.send(
              JSON.stringify({
                type: "ice-candidate",
                candidate: event.candidate,
              }),
            );
          } else {
            log("ICE gathering complete");
          }
        };

        pc.oniceconnectionstatechange = () => {
          log("ICE state: " + pc.iceConnectionState);
          setStatus("ICE: " + pc.iceConnectionState);
          if (
            pc.iceConnectionState === "connected" ||
            pc.iceConnectionState === "completed"
          ) {
            setStatus("Connected peer-to-peer! 🎉");
          }
        };

        // Handle incoming data channel (receiver side)
        pc.ondatachannel = (event) => {
          log("Incoming data channel: " + event.channel.label);
          setupDataChannel(event.channel);
        };
      }

      // ========== 3. Sender Flow ==========
      async function startAsSender() {
        createPeerConnection();

        // Sender creates the data channel
        const ch = pc.createDataChannel("chat");
        setupDataChannel(ch);

        const offer = await pc.createOffer();
        await pc.setLocalDescription(offer);
        log("Sending offer to peer via signaling server");
        ws.send(JSON.stringify(pc.localDescription));
      }

      // ========== 4. Receiver Flow ==========
      async function startAsReceiver(offer) {
        createPeerConnection();

        await pc.setRemoteDescription(new RTCSessionDescription(offer));
        const answer = await pc.createAnswer();
        await pc.setLocalDescription(answer);
        log("Sending answer to peer via signaling server");
        ws.send(JSON.stringify(pc.localDescription));
      }

      // ========== 5. Data Channel Setup ==========
      function setupDataChannel(channel) {
        dataChannel = channel;
        dataChannel.onopen = () => {
          log("Data channel OPEN!");
          setStatus("Data channel open — chat away!");
          chatSection.style.display = "block";
        };
        dataChannel.onclose = () => {
          log("Data channel closed");
          setStatus("Data channel closed");
        };
        dataChannel.onmessage = (event) => {
          receivedMessagesDiv.innerHTML += `<p class="received">Peer: ${event.data}</p>`;
          receivedMessagesDiv.scrollTop = receivedMessagesDiv.scrollHeight;
        };
      }

      // ========== 6. Chat ==========
      sendButton.onclick = () => {
        const message = messageInput.value.trim();
        if (!message || !dataChannel || dataChannel.readyState !== "open")
          return;
        dataChannel.send(message);
        receivedMessagesDiv.innerHTML += `<p class="sent">You: ${message}</p>`;
        receivedMessagesDiv.scrollTop = receivedMessagesDiv.scrollHeight;
        messageInput.value = "";
      };

      messageInput.addEventListener("keydown", (e) => {
        if (e.key === "Enter" && !e.shiftKey) {
          e.preventDefault();
          sendButton.click();
        }
      });
    </script>

    <footer>
      Built by
      <a
        href="https://arifulislamat.com"
        target="_blank"
        rel="noopener noreferrer"
        >Ariful Islam</a
      >
      · WebRTC Learning Playground
    </footer>
  </body>
</html>