Socket io Throws error : You are trying to attach socket.io to an express request handler function

Question

我是 WebSocket 的新手，所以我正在尝试制作一个使用 WebSocket 实时更新的应用程序。这是我的代码：

const PORT = process.env.PORT || 3000;
const INDEX = "./index.html";

const socketIO = require("socket.io");
const express = require("express");

const app = express();

app.get("/", (req, res) => {
    res.sendFile(INDEX, { root: __dirname });
});
app.listen(PORT, () => {
    console.log("SERVER LISTENING ON PORT http://localhost:3000");
});

const io = socketIO(app);
io.on("connection", (socket) => {
    console.log("Client connected");
    socket.on("disconnect", () => console.log("Client disconnected"));
});

此代码抛出如下错误：

错误：您正在尝试将 socket.io 附加到快速请求处理函数。请传递一个http.Server实例。

但是当我写代码时如下：

const PORT = process.env.PORT || 3000;
const INDEX = "/index.html";

const socketIO = require("socket.io");
const express = require("express");
const server = express()
    .get("/", (req, res) => res.sendFile(INDEX, { root: __dirname }))
    .use("/static", express.static("static"))
    .listen(PORT, () => console.log(`Listening on ${PORT}`));
const io = socketIO(server);
io.on("connection", (socket) => {
    console.log("Client connected");
    socket.on("disconnect", () => console.log("Client disconnected"));
});

它很管用。

请帮帮我这是怎么回事。

提前致谢！！！

Answer 1

socket.io 期望从 app.listen 方法返回一个实例（其中 app 是一个快速实例）

在第 1 段代码中，您传递了一个 express 实例，正如我上面提到的，这是错误的

第一段代码的修复，让您更好地理解它

const PORT = process.env.PORT || 3000
const INDEX = './index.html'

const socketIO = require('socket.io')
const express = require('express')

const app = express()
const server = app.listen(PORT, () => {
  console.log('SERVER LISTENING ON PORT http://localhost:3000')
})
const io = socketIO(server)

app.get('/', (req, res) => {
  res.sendFile(INDEX, { root: __dirname })
})

io.on('connection', (socket) => {
  console.log('Client connected')
  socket.on('disconnect', () => console.log('Client disconnected'))
})

Socket io Throws error : You are trying to attach socket.io to an express request handler function

Socket io Throws error : You are trying to attach socket.io to an express request handler function

javascript

node.js

express

sockets

socket.io