Example with passport-jwt

This example shows how to retrieve the authentication context from a basic Express + Passport application.

Please read the related guide: https://socket.io/how-to/use-with-jwt

How to use

$ npm ci && npm start

And point your browser to http://localhost:3000. Optionally, specify a port by supplying the PORT env variable.

How it works

The client sends the JWT in the headers:

const socket = io({
  extraHeaders: {
    authorization: `bearer token`
  }
});

And the Socket.IO server then parses the token and retrieves the user context:

io.engine.use((req, res, next) => {
  const isHandshake = req._query.sid === undefined;
  if (isHandshake) {
    passport.authenticate("jwt", { session: false })(req, res, next);
  } else {
    next();
  }
});