Ping-pong for latency doesnt seem to work anymore

You want to:

• report a bug
• request a feature

Current behaviour

What is actually happening?

Pong event on the client is not fired/triggered, even with pingInterval enabled/set on the server

Steps to reproduce (if the current behaviour is a bug)

https://github.com/Tiboonn/socket.io-fiddle In the fork above the version of socket.io and socket.io-client are 3.0.0 which the ‘pong’ event doesnt work on. If you change both versions in the packege.json to 2.3.0 and reinstall the packages the ‘pong’ event is working

Expected behaviour

What is expected?

I am expecting to get the latency is ms with the following code block on the client side

socket.on('pong', function (ms) {
    console.log(ms)
})

Setup

• OS: Ubuntu 20.04
• browser: Firefox/Chrome (tested multiple)
• socket.io version: 3.0.0

Other information (e.g. stacktraces, related issues, suggestions how to fix)

[darrachequesne]

Hi! You are absolutely right, this should be included in the migration guide.

You should be able to reproduce the behavior with:

// server-side
io.on("connection", (socket) => {
  socket.on("ping", (cb) => {
    if (typeof cb === "function")
      cb();
  });
});

// client-side
setInterval(() => {
  const start = Date.now();

  socket.volatile.emit("ping", () => {
    const latency = Date.now() - start;
    // ...
  });
}, 5000);

[darrachequesne]

Added here: https://socket.io/docs/v3/migrating-from-2-x-to-3-0/#No-more-“pong”-event-for-retrieving-latency

Thanks for the feedback 👍