服务器初始化

Once you have installed the Socket.IO server library, you can now init the server. The complete list of options can be found here.

tip

For TypeScript users, it is possible to provide type hints for the events. Please check this.

Initialization

Standalone

CommonJS

const { Server } = require("socket.io");

const io = new Server({ /* options */ });

io.on("connection", (socket) => {
  // ...
});

io.listen(3000);

ES modules

import { Server } from "socket.io";

const io = new Server({ /* options */ });

io.on("connection", (socket) => {
  // ...
});

io.listen(3000);

TypeScript

import { Server } from "socket.io";

const io = new Server({ /* options */ });

io.on("connection", (socket) => {
  // ...
});

io.listen(3000);

You can also pass the port as the first argument:

CommonJS

const { Server } = require("socket.io");

const io = new Server(3000, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

ES modules

import { Server } from "socket.io";

const io = new Server(3000, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

TypeScript

import { Server } from "socket.io";

const io = new Server(3000, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

This implicitly starts a Node.js HTTP server, which can be accessed through io.httpServer.

With an HTTP server

CommonJS

const { createServer } = require("http");
const { Server } = require("socket.io");

const httpServer = createServer();
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

ES modules

import { createServer } from "http";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

TypeScript

import { createServer } from "http";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

With an HTTPS server

CommonJS

const { readFileSync } = require("fs");
const { createServer } = require("https");
const { Server } = require("socket.io");

const httpServer = createServer({
  key: readFileSync("/path/to/my/key.pem"),
  cert: readFileSync("/path/to/my/cert.pem")
});

const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

ES modules

import { readFileSync } from "fs";
import { createServer } from "https";
import { Server } from "socket.io";

const httpServer = createServer({
  key: readFileSync("/path/to/my/key.pem"),
  cert: readFileSync("/path/to/my/cert.pem")
});

const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

TypeScript

import { readFileSync } from "fs";
import { createServer } from "https";
import { Server } from "socket.io";

const httpServer = createServer({
  key: readFileSync("/path/to/my/key.pem"),
  cert: readFileSync("/path/to/my/cert.pem")
});

const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

See also: Node.js documentation

With client-certificate authentication:

Server

import { readFileSync } from "fs";
import { createServer } from "https";
import { Server } from "socket.io";

const httpServer = createServer({
  key: readFileSync("/path/to/server-key.pem"),
  cert: readFileSync("/path/to/server-cert.pem"),
  requestCert: true,
  ca: [
    readFileSync("/path/to/client-cert.pem")
  ]
});

const io = new Server(httpServer, { /* options */ });

io.engine.on("connection", (rawSocket) => {
  // if you need the certificate details (it is no longer available once the handshake is completed)
  rawSocket.peerCertificate = rawSocket.request.client.getPeerCertificate();
});

io.on("connection", (socket) => {
  console.log(socket.conn.peerCertificate);
  // ...
});

httpServer.listen(3000);

Client

import { readFileSync } from "fs";
import { io } from "socket.io-client";

const socket = io("https://example.com", {
  key: readFileSync("/path/to/client-key.pem"),
  cert: readFileSync("/path/to/client-cert.pem"),
  ca: [
    readFileSync("/path/to/server-cert.pem")
  ]
});

With an HTTP/2 server

CommonJS

const { readFileSync } = require("fs");
const { createSecureServer } = require("http2");
const { Server } = require("socket.io");

const httpServer = createSecureServer({
  allowHTTP1: true,
  key: readFileSync("/path/to/my/key.pem"),
  cert: readFileSync("/path/to/my/cert.pem")
});

const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

ES modules

import { readFileSync } from "fs";
import { createSecureServer } from "http2";
import { Server } from "socket.io";

const httpServer = createSecureServer({
  allowHTTP1: true,
  key: readFileSync("/path/to/my/key.pem"),
  cert: readFileSync("/path/to/my/cert.pem")
});

const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

TypeScript

import { readFileSync } from "fs";
import { createSecureServer } from "http2";
import { Server } from "socket.io";

const httpServer = createSecureServer({
  allowHTTP1: true,
  key: readFileSync("/path/to/my/key.pem"),
  cert: readFileSync("/path/to/my/cert.pem")
});

const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

See also: Node.js documentation

With Express

CommonJS

const express = require("express");
const { createServer } = require("http");
const { Server } = require("socket.io");

const app = express();
const httpServer = createServer(app);
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

ES modules

import express from "express";
import { createServer } from "http";
import { Server } from "socket.io";

const app = express();
const httpServer = createServer(app);
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

TypeScript

import * as express from "express";
import { createServer } from "http";
import { Server } from "socket.io";

const app = express();
const httpServer = createServer(app);
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

caution

Using app.listen(3000) will not work here, as it creates a new HTTP server.

More information here.

With Koa

CommonJS

const Koa = require("koa");
const { createServer } = require("http");
const { Server } = require("socket.io");

const app = new Koa();
const httpServer = createServer(app.callback());
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

ES modules

import Koa from "koa";
import { createServer } from "http";
import { Server } from "socket.io";

const app = new Koa();
const httpServer = createServer(app.callback());
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

TypeScript

import * as Koa from "koa";
import { createServer } from "http";
import { Server } from "socket.io";

const app = new Koa();
const httpServer = createServer(app.callback());
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

More information here.

With Nest

See the documentation here.

caution

NestJS v7 and below relies on Socket.IO v2, while NestJS v8 relies on Socket.IO v4. Please use a compatible client.

With Fastify

You need to register the fastify-socket.io plugin:

CommonJS

const fastify = require("fastify");
const fastifyIO = require("fastify-socket.io");

const server = fastify();
server.register(fastifyIO);

server.get("/", (req, reply) => {
  server.io.emit("hello");
});

server.ready().then(() => {
  // we need to wait for the server to be ready, else `server.io` is undefined
  server.io.on("connection", (socket) => {
    // ...
  });
});

server.listen(3000);

ES modules

import fastify from "fastify";
import fastifyIO from "fastify-socket.io";

const server = fastify();
server.register(fastifyIO);

server.get("/", (req, reply) => {
  server.io.emit("hello");
});

server.ready().then(() => {
  // we need to wait for the server to be ready, else `server.io` is undefined
  server.io.on("connection", (socket) => {
    // ...
  });
});

server.listen(3000);

TypeScript

import fastify from "fastify";
import fastifyIO from "fastify-socket.io";

const server = fastify();
server.register(fastifyIO);

server.get("/", (req, reply) => {
  server.io.emit("hello");
});

server.ready().then(() => {
  // we need to wait for the server to be ready, else `server.io` is undefined
  server.io.on("connection", (socket) => {
    // ...
  });
});

server.listen(3000);

With µWebSockets.js

import { App } from "uWebSockets.js";
import { Server } from "socket.io";

const app = new App();
const io = new Server();

io.attachApp(app);

io.on("connection", (socket) => {
  // ...
});

app.listen(3000, (token) => {
  if (!token) {
    console.warn("port already in use");
  }
});

Reference: https://github.com/uNetworking/uWebSockets.js

Options

The complete list of available options can be found here.