Build a Hyperliquid Analytics Dashboard

import { createServer } from "node:http";
import { WebSocketServer, WebSocket } from "ws";

const API_KEY = process.env.UNIBLOCK_API_KEY;
const INFO_URL = "https://api.uniblock.dev/uni/v1/hyperliquid/info";
const WSS_URL = "wss://websocket.uniblock.dev/goldrush";

// --- REST: forward the body verbatim, inject the key ---
const server = createServer(async (req, res) => {
  if (req.method !== "POST" || !req.url.startsWith("/api/info")) {
    res.writeHead(404).end();
    return;
  }
  const url = new URL(req.url, "http://localhost");
  const upstream = new URL(INFO_URL);
  upstream.searchParams.set("chainId", url.searchParams.get("chainId") ?? "999");
  // Let the client pin a provider when it needs one (see below).
  const provider = url.searchParams.get("provider");
  if (provider) upstream.searchParams.set("provider", provider);

  const chunks = [];
  for await (const chunk of req) chunks.push(chunk);

  const r = await fetch(upstream, {
    method: "POST",
    headers: { "X-API-KEY": API_KEY, "content-type": "application/json" },
    body: Buffer.concat(chunks),
  });
  res.writeHead(r.status, { "content-type": "application/json" });
  res.end(Buffer.from(await r.arrayBuffer()));
});

// --- WebSocket: bridge browser <-> Uniblock, inject the key ---
const wss = new WebSocketServer({ noServer: true });

server.on("upgrade", (req, socket, head) => {
  if (new URL(req.url, "http://localhost").pathname !== "/ws") return socket.destroy();

  wss.handleUpgrade(req, socket, head, (client) => {
    const upstream = new WebSocket(WSS_URL, { headers: { "X-API-KEY": API_KEY } });
    const pending = [];

    // The browser may subscribe before the upstream socket is open, so buffer until then.
    upstream.on("open", () => {
      for (const msg of pending) upstream.send(msg);
      pending.length = 0;
    });
    upstream.on("message", (data) => {
      if (client.readyState === WebSocket.OPEN) client.send(data);
    });
    client.on("message", (data) => {
      const msg = data.toString();
      if (upstream.readyState === WebSocket.OPEN) upstream.send(msg);
      else pending.push(msg);
    });

    const closeBoth = () => {
      client.close();
      upstream.close();
    };
    client.on("close", closeBoth);
    upstream.on("close", closeBoth);
    upstream.on("error", closeBoth);
  });
});

server.listen(8787);

async function info(body, opts = {}) {
  const qs = new URLSearchParams({ chainId: "999", ...opts });
  const res = await fetch(`/api/info?${qs}`, {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify(body),
  });
  if (!res.ok) throw new Error(`info ${body.type} failed: ${res.status}`);
  return res.json();
}

// Wrong. String concatenation, not addition: "7500.00" + "42.10" === "7500.0042.10"
const wrong = position.positionValue + position.unrealizedPnl;

// Right. Convert at the edge, where you're formatting
const right = Number(position.positionValue) + Number(position.unrealizedPnl);