Remove `upgrade` event from example

[samlior]

According to engine.io doc, it looks like the socket no longer emits the upgrade event, so it should be removed from this example.

By the way, I would like to ask how I should add some verification information in the upgrade request header, and reject the upgrade if the verification information is illegal.

[darrachequesne]

Hi! The upgrade event was indeed missing from the documentation, this should be fixed now (https://github.com/socketio/engine.io/commit/535b068670848f6a3193528582484826a858d680).

how I should add some verification information in the upgrade request header, and reject the upgrade if the verification information is illegal.

You can manually handle the upgrade event of the Node.js HTTP server:

import { createServer } from "http";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer);

httpServer.removeAllListeners("upgrade");

httpServer.on("upgrade", (req, socket, head) => {
  // do some verification...

  // then
  io.engine.handleUpgrade(req, socket, head);
});

httpServer.listen(3000);

Reference: https://nodejs.org/api/http.html#event-upgrade_1

[samlior]

Thank you so much!