0 x01 cause:

Socketio was used to set up the signaling server, express and Socketio were used as the server, and 95% of blogs on the Internet were referred to, and the problem of CORS was found. After half a day of torturing, most of the posts were not successful. Finally, I tried to make a successful attempt by referring to a post on Github.

const express = require('express');
const  app = express();
const http = require('http').Server(app);
let path = require('path');
var cors = require('cors');

app.use(cors());

const io = require('socket.io')(http,{
cors: {origin:"http://127.0.0.1:8081".methods: ["GET"."POST"].credentials: true.allowEIO3: true
},
transport: ['websocket']}); io.on('connection'.function(socket) {
    console.log('A user connected');
    
    //Whenever someone disconnects this piece of code executed
    socket.on('disconnect'.function () {
    console.log('A user disconnected');
    });

    socket.on('login'.function (obj) {                
         console.log(obj.username);
              // Send data
         socket.emit('relogin', {
                msg: Hi `${obj.username}`.code: 200
              });  
          });


    });
    
    http.listen(3000.function() {
    console.log('listening on *:3000');
    });



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Client code


 import VueSocketIO from 'vue-socket.io'
 import SocketIO from 'socket.io-client'
  
  Vue.use(new VueSocketIO({
    debug: true.connection: SocketIO('http://127.0.0.1:3000'),
    extraHeaders: {
        'Access-Control-Allow-Credentials':true
    },
    allowEIO3:true.vuex: {
        store,
        actionPrefix: 'SOCKET_'.mutationPrefix: 'SOCKET_'}}));Copy the code