Implement P2P polling app with Yjs and WebRTC

Uses Yjs CRDTs for conflict-free shared state and y-webrtc for peer-to-peer data exchange. Users can add poll options and vote/unvote, with all changes syncing in real-time across connected peers. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-03-15 04:32:06 +01:00
7 changed files with 1769 additions and 207 deletions
--- a/PollingApp.html
+++ b/PollingApp.html
@@ -1,200 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-<head>
-<meta charset="UTF-8">
-<title>Peer‑to‑Peer Poll – up to 14 users (no vote loops)</title>
-<style>
-  body {font-family:Arial,Helvetica,sans-serif; margin:20px;}
-  #options li {margin:5px 0;}
-  button {margin-left:5px;}
-</style>
-</head>
-<body>
-
-<h2>Peer‑to‑Peer Poll (max 14 participants)</h2>
-
-<div id="setup">
-  <label>Your Peer ID: <input id="myId" readonly size="30"></label><br><br>
-  <label>Room host ID (leave empty if you are the first client):
-    <input id="hostId" placeholder="host peer id">
-  </label>
-  <button id="joinBtn">Join / Create Room</button>
-  <p id="status"></p>
-</div>
-
-<hr>
-
-<h3>Poll</h3>
-<ul id="options"></ul>
-
-<input id="newOption" placeholder="New option text">
-<button id="addOptionBtn">Add option</button>
-
-<script src="https://unpkg.com/peerjs@1.5.4/dist/peerjs.min.js"></script>
-<script>
-/* ---------- 1. Initialise PeerJS ---------- */
-const peer = new Peer();                     // public signalling server
-const myIdInput = document.getElementById('myId');
-const statusEl   = document.getElementById('status');
-
-let isHost = false;                          // true for the first client
-let connections = [];                        // all open DataConnections
-let knownPeers = new Set();                  // IDs of every peer we know (including host)
-
-peer.on('open', id => {
-  myIdInput.value = id;
-  statusEl.textContent = 'Enter a host ID (or leave empty) and click Join.';
-});
-
-/* ---------- 2. Accept incoming connections (host side) ---------- */
-peer.on('connection', incoming => {
-  registerConnection(incoming);
-});
-
-/* ---------- 3. Join / create a room ---------- */
-document.getElementById('joinBtn').onclick = () => {
-  const hostId = document.getElementById('hostId').value.trim();
-  if (hostId) {
-    isHost = false;
-    connectToPeer(hostId);
-    statusEl.textContent = `Connecting to host ${hostId}…`;
-  } else {
-    isHost = true;
-    knownPeers.add(peer.id);
-    statusEl.textContent = 'Room created – share this Peer ID with others.';
-  }
-};
-
-/* ---------- 4. Helper: connect to a remote peer ---------- */
-function connectToPeer(peerId) {
-  if (knownPeers.has(peerId)) return;
-  const conn = peer.connect(peerId);
-  registerConnection(conn);
-}
-
-/* ---------- 5. Register a DataConnection ---------- */
-function registerConnection(conn) {
-  if (!conn) return;
-  connections.push(conn);
-  knownPeers.add(conn.peer);
-
-  conn.on('open', () => {
-    // 1️⃣ Send full poll state
-    conn.send({type: 'full', payload: poll, msgId: crypto.randomUUID()});
-
-    // 2️⃣ If we are the host, tell the newcomer about other peers
-    if (isHost) {
-      const others = Array.from(knownPeers).filter(id => id !== conn.peer && id !== peer.id);
-      if (others.length) conn.send({type: 'peer-list', payload: others, msgId: crypto.randomUUID()});
-    }
-  });
-
-  conn.on('data', data => handleMessage(data, conn.peer));
-  conn.on('close', () => {
-    connections = connections.filter(c => c !== conn);
-    knownPeers.delete(conn.peer);
-  });
-}
-
-/* ---------- 6. Shared poll state ---------- */
-let poll = {options: []};   // each option: {id, text, votes}
-
-/* ---------- 7. Track my own votes ---------- */
-const myVotes = new Set();   // option.id values
-
-/* ---------- 8. Remember which messages we already processed ---------- */
-const seenMsgIds = new Set();
-
-/* ---------- 9. Broadcast helper (skip the sender) ---------- */
-function broadcast(msg, except = null) {
-  connections.forEach(c => {
-    if (c.open && c.peer !== except) c.send(msg);
-  });
-}
-
-/* ---------- 10. Message handling ---------- */
-function handleMessage(msg, senderId) {
-  // Ignore duplicates
-  if (seenMsgIds.has(msg.msgId)) return;
-  seenMsgIds.add(msg.msgId);
-
-  switch (msg.type) {
-    case 'full':
-      poll = msg.payload;
-      render();
-      break;
-
-    case 'add':
-      poll.options.push(msg.payload);
-      render();
-      broadcast(msg, senderId);   // forward once
-      break;
-
-    case 'vote':
-      const opt = poll.options.find(o => o.id === msg.payload.id);
-      if (opt) opt.votes++;
-      render();
-      broadcast(msg, senderId);
-      break;
-
-    case 'peer-list':
-      msg.payload.forEach(id => {
-        if (id !== peer.id && !knownPeers.has(id)) connectToPeer(id);
-      });
-      break;
-  }
-}
-
-/* ---------- 11. UI rendering ---------- */
-function render() {
-  const ul = document.getElementById('options');
-  ul.innerHTML = '';
-  poll.options.forEach(opt => {
-    const li = document.createElement('li');
-    li.textContent = `${opt.text} – ${opt.votes} vote(s)`;
-
-    const btn = document.createElement('button');
-    btn.textContent = myVotes.has(opt.id) ? 'Voted' : 'Vote';
-    btn.disabled = myVotes.has(opt.id);
-    btn.onclick = () => {
-      // Record locally – prevents double‑click on the same client
-      myVotes.add(opt.id);
-      btn.textContent = 'Voted';
-      btn.disabled = true;
-
-      const voteMsg = {
-        type: 'vote',
-        payload: {id: opt.id},
-        msgId: crypto.randomUUID()
-      };
-      // Apply locally first
-      opt.votes++;
-      render();
-      // Send to all peers
-      broadcast(voteMsg);
-    };
-    li.appendChild(btn);
-    ul.appendChild(li);
-  });
-}
-
-/* ---------- 12. Add new option ---------- */
-document.getElementById('addOptionBtn').onclick = () => {
-  const txt = document.getElementById('newOption').value.trim();
-  if (!txt) return;
-  const option = {id: crypto.randomUUID(), text: txt, votes: 0};
-  poll.options.push(option);
-  render();
-
-  const addMsg = {
-    type: 'add',
-    payload: option,
-    msgId: crypto.randomUUID()
-  };
-  broadcast(addMsg);
-  document.getElementById('newOption').value = '';
-};
-</script>
-</body>
-</html>
-
--- a/README.md
+++ b/README.md
@@ -1,7 +1 @@
 # P2P Poll App
-
-This is a very simple polling app using peerjs.
-It runs as a single HTML file and can handle multiple users in one poll room.
-The app once open is self explanatory.
-App created with the help of GPTOSS120B.
-
--- a/index.html
+++ b/index.html
@@ -0,0 +1,33 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>P2P Poll</title>
+  <link rel="stylesheet" href="/src/style.css">
+</head>
+<body>
+  <div id="app">
+    <header>
+      <h1>P2P Poll</h1>
+      <div id="status">
+        <span id="connection-status" class="connecting">Connecting...</span>
+        <span id="peer-count">1 peer</span>
+      </div>
+    </header>
+
+    <main>
+      <div id="add-option">
+        <input type="text" id="option-input" placeholder="Add a poll option..." maxlength="100">
+        <button id="add-btn">Add</button>
+      </div>
+
+      <div id="poll-options"></div>
+
+      <p id="empty-state">No options yet. Add one above!</p>
+    </main>
+  </div>
+
+  <script type="module" src="/src/main.js"></script>
+</body>
+</html>
--- a/package-lock.json
+++ b/package-lock.json
--- a/package.json
+++ b/package.json
@@ -0,0 +1,18 @@
+{
+  "name": "p2p-poll",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "yjs": "^13.6.0",
+    "y-webrtc": "^10.3.0"
+  },
+  "devDependencies": {
+    "vite": "^6.0.0"
+  }
+}
--- a/src/main.js
+++ b/src/main.js
@@ -0,0 +1,136 @@
+import * as Y from 'yjs';
+import { WebrtcProvider } from 'y-webrtc';
+
+// --- Peer ID (stable across reloads) ---
+
+function getOrCreatePeerId() {
+  let id = localStorage.getItem('peer-id');
+  if (!id) {
+    id = crypto.randomUUID();
+    localStorage.setItem('peer-id', id);
+  }
+  return id;
+}
+
+const peerId = getOrCreatePeerId();
+
+// --- Room name from URL ---
+
+function getRoomName() {
+  const params = new URLSearchParams(window.location.search);
+  return params.get('room') || 'default-poll';
+}
+
+const roomName = getRoomName();
+
+// --- Yjs setup ---
+
+const ydoc = new Y.Doc();
+const provider = new WebrtcProvider(roomName, ydoc);
+const yOptions = ydoc.getMap('poll-options');
+
+// --- Data operations ---
+
+function addOption(name) {
+  const id = crypto.randomUUID();
+  const optionMap = new Y.Map();
+  optionMap.set('name', name);
+  optionMap.set('votes', new Y.Map());
+  yOptions.set(id, optionMap);
+}
+
+function toggleVote(optionId) {
+  const optionMap = yOptions.get(optionId);
+  if (!optionMap) return;
+  const votes = optionMap.get('votes');
+  if (votes.has(peerId)) {
+    votes.delete(peerId);
+  } else {
+    votes.set(peerId, true);
+  }
+}
+
+// --- UI rendering ---
+
+const container = document.getElementById('poll-options');
+const emptyState = document.getElementById('empty-state');
+
+function render() {
+  container.innerHTML = '';
+
+  const entries = [];
+  yOptions.forEach((optionMap, id) => {
+    entries.push({
+      id,
+      name: optionMap.get('name'),
+      votes: optionMap.get('votes').size,
+      voted: optionMap.get('votes').has(peerId),
+    });
+  });
+
+  entries.sort((a, b) => b.votes - a.votes || a.name.localeCompare(b.name));
+
+  emptyState.className = entries.length > 0 ? 'hidden' : '';
+
+  for (const entry of entries) {
+    const div = document.createElement('div');
+    div.className = 'poll-option';
+
+    const nameSpan = document.createElement('span');
+    nameSpan.className = 'option-name';
+    nameSpan.textContent = entry.name;
+
+    const voteCount = document.createElement('span');
+    voteCount.className = 'vote-count';
+    voteCount.textContent = entry.votes;
+
+    const voteBtn = document.createElement('button');
+    voteBtn.className = entry.voted ? 'vote-btn voted' : 'vote-btn';
+    voteBtn.textContent = entry.voted ? 'Unvote' : 'Vote';
+    voteBtn.addEventListener('click', () => toggleVote(entry.id));
+
+    div.append(nameSpan, voteCount, voteBtn);
+    container.appendChild(div);
+  }
+}
+
+// Re-render on any change in the shared state
+yOptions.observeDeep(() => render());
+
+// --- Add option handlers ---
+
+const input = document.getElementById('option-input');
+const addBtn = document.getElementById('add-btn');
+
+addBtn.addEventListener('click', () => {
+  const name = input.value.trim();
+  if (name) {
+    addOption(name);
+    input.value = '';
+  }
+});
+
+input.addEventListener('keydown', (e) => {
+  if (e.key === 'Enter') addBtn.click();
+});
+
+// --- Connection status & peer count ---
+
+const statusEl = document.getElementById('connection-status');
+const peerCountEl = document.getElementById('peer-count');
+
+provider.on('synced', ({ synced }) => {
+  statusEl.textContent = synced ? 'Connected' : 'Connecting...';
+  statusEl.className = synced ? 'connected' : 'connecting';
+});
+
+function updatePeerCount() {
+  const count = provider.awareness.getStates().size;
+  peerCountEl.textContent = `${count} peer${count !== 1 ? 's' : ''}`;
+}
+
+provider.awareness.on('change', updatePeerCount);
+updatePeerCount();
+
+// --- Initial render ---
+render();
--- a/src/style.css
+++ b/src/style.css
@@ -0,0 +1,144 @@
+* {
+  margin: 0;
+  padding: 0;
+  box-sizing: border-box;
+}
+
+body {
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
+  background: #f5f5f5;
+  color: #333;
+  min-height: 100vh;
+}
+
+#app {
+  max-width: 600px;
+  margin: 0 auto;
+  padding: 2rem 1rem;
+}
+
+header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  margin-bottom: 2rem;
+}
+
+h1 {
+  font-size: 1.5rem;
+}
+
+#status {
+  display: flex;
+  gap: 1rem;
+  font-size: 0.85rem;
+  color: #666;
+}
+
+#connection-status::before {
+  content: "";
+  display: inline-block;
+  width: 8px;
+  height: 8px;
+  border-radius: 50%;
+  margin-right: 4px;
+  vertical-align: middle;
+}
+
+#connection-status.connected::before {
+  background: #4caf50;
+}
+
+#connection-status.connecting::before {
+  background: #ff9800;
+}
+
+#add-option {
+  display: flex;
+  gap: 0.5rem;
+  margin-bottom: 1.5rem;
+}
+
+#option-input {
+  flex: 1;
+  padding: 0.6rem 0.8rem;
+  border: 1px solid #ddd;
+  border-radius: 6px;
+  font-size: 1rem;
+  outline: none;
+}
+
+#option-input:focus {
+  border-color: #2196f3;
+}
+
+#add-btn {
+  padding: 0.6rem 1.2rem;
+  background: #2196f3;
+  color: white;
+  border: none;
+  border-radius: 6px;
+  font-size: 1rem;
+  cursor: pointer;
+}
+
+#add-btn:hover {
+  background: #1976d2;
+}
+
+.poll-option {
+  display: flex;
+  align-items: center;
+  background: white;
+  padding: 0.8rem 1rem;
+  border-radius: 8px;
+  margin-bottom: 0.5rem;
+  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
+}
+
+.option-name {
+  flex: 1;
+  font-size: 1rem;
+}
+
+.vote-count {
+  font-size: 0.9rem;
+  font-weight: 600;
+  color: #666;
+  margin-right: 0.75rem;
+  min-width: 1.5rem;
+  text-align: center;
+}
+
+.vote-btn {
+  padding: 0.4rem 1rem;
+  border: 2px solid #2196f3;
+  border-radius: 6px;
+  font-size: 0.85rem;
+  cursor: pointer;
+  background: white;
+  color: #2196f3;
+}
+
+.vote-btn:hover {
+  background: #e3f2fd;
+}
+
+.vote-btn.voted {
+  background: #2196f3;
+  color: white;
+}
+
+.vote-btn.voted:hover {
+  background: #1976d2;
+}
+
+#empty-state {
+  text-align: center;
+  color: #999;
+  padding: 2rem;
+}
+
+#empty-state.hidden {
+  display: none;
+}