WebSocket Streaming

const API_KEY = "YOUR_API_KEY";

const ws = new WebSocket(
  `wss://therundown.io/api/v2/ws/markets?key=${API_KEY}&sport_ids=4&market_ids=1,2,3`
);

ws.onopen = () => {
  console.log("Connected to V2 Markets WebSocket");
};

ws.onmessage = (event) => {
  const msg = JSON.parse(event.data);

  // Handle heartbeat
  if (msg.meta?.type === "heartbeat") {
    console.log("Heartbeat received");
    return;
  }

  // Process market price update
  const d = msg.data;
  console.log(
    `Update: event=${d.event_id} market=${d.market_id} aff=${d.affiliate_id}`
  );
  console.log(
    `  line=${d.line} price=${d.price} (was ${d.previous_price}, delta=${d.price_delta})`
  );
};

ws.onerror = (error) => {
  console.error("WebSocket error:", error);
};

ws.onclose = (event) => {
  console.log(`WebSocket closed: code=${event.code} reason=${event.reason}`);
};

let lastHeartbeat = Date.now();

ws.onmessage = (event) => {
  const msg = JSON.parse(event.data);

  if (msg.meta?.type === "heartbeat") {
    lastHeartbeat = Date.now();
    return; // Do not process as data
  }

  // Process actual price update
  handleUpdate(msg.data);
};

// Monitor heartbeat health
setInterval(() => {
  const elapsed = Date.now() - lastHeartbeat;
  if (elapsed > 60_000) {
    console.warn("No heartbeat in 60s, reconnecting...");
    ws.close();
    // Trigger reconnection logic
  }
}, 10_000);

function createReconnectingWebSocket(url, onMessage) {
  let ws;
  let reconnectDelay = 1000;
  const MAX_DELAY = 30000;

  function connect() {
    ws = new WebSocket(url);

    ws.onopen = () => {
      console.log("WebSocket connected");
      reconnectDelay = 1000; // Reset backoff
    };

    ws.onmessage = (event) => {
      const msg = JSON.parse(event.data);
      if (msg.meta?.type === "heartbeat") return;
      onMessage(msg.data);
    };

    ws.onclose = () => {
      const jitter = Math.random() * 1000;
      const delay = Math.min(reconnectDelay + jitter, MAX_DELAY);
      console.log(`WebSocket closed. Reconnecting in ${Math.round(delay)}ms...`);

      setTimeout(() => {
        reconnectDelay = Math.min(reconnectDelay * 2, MAX_DELAY);
        connect();
      }, delay);
    };

    ws.onerror = (error) => {
      console.error("WebSocket error:", error);
      ws.close(); // Triggers onclose -> reconnect
    };
  }

  connect();

  return {
    close: () => {
      reconnectDelay = MAX_DELAY + 1; // Prevent reconnection
      ws.close();
    },
  };
}

// Usage
const connection = createReconnectingWebSocket(
  `wss://therundown.io/api/v2/ws/markets?key=${API_KEY}&sport_ids=4`,
  (update) => {
    console.log(`Price update: event=${update.event_id} market=${update.market_id} price=${update.price}`);
  }
);