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Installation

Requirements​

  • Node 18 or newer.
  • A package manager (npm, pnpm, yarn — pick one).

Install​

npm install rtc.io-server

rtc.io-server brings in socket.io@^4.7.4 as a dependency. You don't need to install it separately.

Minimal project​

mkdir my-rtcio-server && cd my-rtcio-server
npm init -y
npm install rtc.io-server

Edit package.json:

package.json
{
  "type": "module",
  "scripts": {
    "start": "node index.js",
    "dev": "node --watch index.js"
  }
}

Create index.js:

index.js
import { Server, RtcioEvents } from "rtc.io-server";

const server = new Server({ cors: { origin: "*" } });

server.on("connection", (socket) => {
  console.log("connected", socket.id);

  socket.on("join-room", ({ roomId, name }) => {
    socket.data.name = name;
    socket.join(roomId);
    socket.to(roomId).emit("user-connected", { id: socket.id, name });
    socket.to(roomId).emit(RtcioEvents.INIT_OFFER, { source: socket.id });
  });

  socket.on("disconnecting", () => {
    socket.rooms.forEach((roomId) => {
      if (roomId === socket.id) return;
      socket.to(roomId).emit("user-disconnected", { id: socket.id });
    });
  });
});

server.listen(3001);
console.log("rtc.io-server listening on 3001");

Run it:

npm run dev

That's a working server.

TypeScript​

Install the TypeScript toolchain:

npm install -D typescript @types/node ts-node-dev

Create tsconfig.json:

tsconfig.json
{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ES2022",
    "moduleResolution": "Bundler",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "outDir": "dist"
  },
  "include": ["**/*.ts"]
}

Update package.json:

package.json
{
  "type": "module",
  "scripts": {
    "dev": "ts-node-dev --respawn index.ts",
    "build": "tsc",
    "start": "node dist/index.js"
  }
}

Rename index.js → index.ts. Same code, with types you can use:

index.ts
import { Server, RtcioEvents, Socket } from "rtc.io-server";

const server = new Server({ cors: { origin: "*" } });

server.on("connection", (socket: Socket) => {
  socket.on("join-room", ({ roomId, name }: { roomId: string; name: string }) => {
    socket.data.name = name;
    socket.join(roomId);
    socket.to(roomId).emit("user-connected", { id: socket.id, name });
    socket.to(roomId).emit(RtcioEvents.INIT_OFFER, { source: socket.id });
  });
});

server.listen(3001);

For a fully typed event surface (events you emit/on), use socket.io's typed-events generics:

type ClientToServer = {
  "join-room": (data: { roomId: string; name: string }) => void;
};

type ServerToClient = {
  "user-connected": (data: { id: string; name: string }) => void;
  "user-disconnected": (data: { id: string }) => void;
};

const server = new Server<ClientToServer, ServerToClient>({ cors: { origin: "*" } });

server.on("connection", (socket) => {
  socket.on("join-room", ({ roomId, name }) => {
    socket.data.name = name;        // typed
    socket.join(roomId);
    socket.to(roomId).emit("user-connected", { id: socket.id, name });   // typed
  });
});

The four generics are ClientToServer, ServerToClient, InterServer, SocketData. See socket.io typed events docs for the full pattern.

Project layout​

A common shape for a real signaling server:

my-rtcio-server/
├─ package.json
├─ tsconfig.json
├─ index.ts                 # entrypoint
├─ src/
│  ├─ rooms.ts             # join-room, leave-room, presence
│  ├─ auth.ts              # io.use middleware
│  ├─ ice.ts               # short-lived TURN credential vending
│  └─ scaling.ts           # adapter setup if you horizontally scale
└─ .env

index.ts wires the pieces:

import { Server } from "rtc.io-server";
import { authMiddleware } from "./src/auth";
import { wireRooms } from "./src/rooms";
import { wireIce } from "./src/ice";

const server = new Server({
  cors: { origin: process.env.ALLOWED_ORIGINS?.split(",") ?? "*" },
});

server.use(authMiddleware);

server.on("connection", (socket) => {
  wireRooms(socket);
  wireIce(socket);
});

server.listen(parseInt(process.env.PORT ?? "3001"));

Each wireX function is a (socket: Socket) => void that registers handlers. Easier to test than one giant connection handler.

Live reload​

For TS, ts-node-dev (above) restarts on file changes. For plain JS, node --watch index.js (Node 18.11+).

Production build​

For TS:

npm run build
node dist/index.js

For plain JS, just node index.js — no build step.

Next​