I am using v2.1.0 and none of the above answers worked for me.
This did though:
import express from "express";
import http from "http";
const app = express();
const server = http.createServer(app);
const sio = 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();
}
});
sio.on("connection", () => {
console.log("Connected!");
});
server.listen(3000);