在将 node.js 用于 socket.io 时遇到问题

Question

io.on('connection', socket =>{ ^

TypeError: io.on is not a function at Object. (D:\shalini course\projects\chat app\nodeserver\nodeapp.js:7:4) at Module._compile (node:internal/modules/cjs/loader:1218:14) at Module._extensions..js (node:internal/modules/cjs/loader:1272:10) at Module.load (node:internal/modules/cjs/loader:1081:32) at Module._load (node:internal/modules/cjs/loader:922:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12) at node:internal/main/run_main_module:23:47

it shows this error when I run a cmd - node nodeapp.js please do reply If any idea how to fix it?

enter image description here I tried running an application of socket.io on 5000 port using node.js but it's not working.

Answer 1

you have to add the socket.io server to the http server, the mistake you are doing is that you are adding the socket.io server to nowhere, to the aire, try with this before to iniltialize the server on port 5000

//CREATE THE SERVER NODE JS
const server = http.createServer(app)


// CREATE SOCKET.IO SERVER CONNECT WITH OUR SERVER
const io = new Server(server);


HERE PUT YOUR SOCKET IO CODE, io.on,.....

server.listen(port,()=>{
    console.log(`listening on port ${port}`)
});

Answer 2

• Yes, "io" that you are trying to use a method on is not a function on that class in your code "io" includes the whole package of socketio all the classes and functions
• "io" in your code has all the classes that your can use by

    const myClass = new io.(someclass)()

• You can impove your code like this

    const socketiopackage = require('socket.io')
    const port = 5000
    const io = new socketiopackage.Server(5000,{cors: {"Access-Control-Allow-Origin": "*",methods: ["GET", "POST", "OPTIONS"]},})
    var users = {}
    
    io.on('connection',socket=>{
        socket.on('new-user-joined',name=>{
            users[socket.id]=name
            socket.broadcast.emit('user-joined',name)
        })
        socket.on('send',message=>{
            socket.broadcast.emit('recieve',{message,name:user[socket.id]})
        })
    })

• or it is easier to directly import your required class

    const { Server } = require('socket.io')
    const port = 5000
    const io = new Server(5000,{cors: {"Access-Control-Allow-Origin": "*",methods: ["GET", "POST", "OPTIONS"]},})
    var users = {}
    
    io.on('connection',socket=>{
        socket.on('new-user-joined',name=>{
            users[socket.id]=name
            socket.broadcast.emit('user-joined',name)
        })
        socket.on('send',message=>{
            socket.broadcast.emit('recieve',{message,name:user[socket.id]})
        })
    })

• I have added some cors settings in the options for creating a server, it is a good practice to do so

Using Nodemon

• install it using

npm install -g nodemon

• then use it using

nodemon (fileName).js