Socket.io and node JS resulting CORS blocked issue - node.js

Question

I've been working on chat functionality. There are two kinds of clients, One is the frontend of my application and the second is random another website.
I know there are plenty of issues like this but I tried all of the solution but I'm still getting following error:
Access to XMLHttpRequest at 'https://mydomain/socket.io/?EIO=3&transport=polling&t=NCjoM1w' from origin 'null' has been blocked by CORS policy: The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.
and this the error I'm getting on client-side of my own front end:
https://mydomain/socket.io/?EIO=3&transport=polling&t=NCjnJUX 404 (Not Found)
This is how I'm trying to connect from client-side.
var socket = io.connect("https://mydomain:443/", {secure: true, port: '443'});
and this is my server.js code
const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const passport = require("passport");
const users = require("./routes/api/users");
const base = require("./routes/api/base");
const leads = require("./routes/api/leads");
const requests = require("./routes/api/requests");
const offApp = require("./routes/api/offApp");
const chat = require("./routes/api/chat");
const chatSocket = require("./routes/socket/chat");
const path = require("path"); // on top
const app = express();
// const client = require('socket.io').listen(4000).sockets;
const https = require('https');
const fs = require('fs');
var options = {
pfx: fs.readFileSync('certificate.pfx'),
passphrase: 'password'
};
app.all('/*', function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization, Content-Length, X-Requested-With, *');
next();
});
var server = https.createServer(options, app);
var client = require("socket.io").listen(server);
client.origins('*:*') ;
server.listen(443);
// Bodyparser middleware
app.use(
bodyParser.urlencoded({
extended: false
})
);
app.use(bodyParser.json());
// DB Config
const db = require("./config/keys").mongoURI;
// Connect to MongoDB
mongoose
.connect(
db,
{ useNewUrlParser: true }, (err, db) => {
if (err) {
throw err;
}
console.log('MongoDB connected');
chatSocket(db, client);
});
// Passport middleware
app.use(passport.initialize());
// Passport config
require("./config/passport")(passport);
// Routes
app.use("/api/users", users);
app.use("/api/base", base);
app.use("/api/leads", leads);
app.use("/api/requests", requests);
app.use("/api/offapp", offApp);
app.use("/api/chat", chat);
const port = process.env.PORT || 5000;
app.use(express.static("client/build")); // change this if your dir structure is different
app.get("*", (req, res) => {
res.sendFile(path.resolve(__dirname, "client", "build", "index.html"));
});
app.listen(port, () => console.log(`Server up and running on port ${port} !`));
Please help me resolve this CORS and other issues. I am using the Azure app service. That's why I can't use any other port than 80 and 433

Answer 1

Install cors package using npm i cors
In your app.js file,
const cors = require('cors')
app.use(cors());

Answer 2

// use CORS like that-
// you need to use it as middle ware
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*"); // update to match the domain you will make the request from
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});

Answer 3

Danish try this solution, I hope it will work
const client = require("socket.io")(server, {
handlePreflightRequest: (req, res) => {
const headers = {
"Access-Control-Allow-Headers": "Content-Type, Authorization",
"Access-Control-Allow-Origin": req.headers.origin, //or the specific origin you want to give access to,
"Access-Control-Allow-Credentials": true
};
res.writeHead(200, headers);
res.end();
}
});
client.on("connection", () => {
console.log("Connected!");
});
server.listen(443);