Realtime Broadcast service's broadcast handlers don't receive messages

[Danziger]

Messages sent using the Realtime Broadcast service are sent and received, but the supabase-js client will never invoke the corresponding event listener.

The issue seems to be on this line:

https://github.com/supabase/supabase-js/blob/master/packages/core/realtime-js/src/RealtimeChannel.ts#L874

As bind.callback(handledPayload, ref) returns a function (the event listener), so it should be bind.callback(handledPayload, ref)() for the event listener to be invoked.

To Reproduce

I have an app where users are able to join a group and broadcast messages to that group. This is the relevant code, based on the examples in Supabase's docs:

await supabseClient.realtime.setAuth();

const channel = supabseClient.channel('test', {
  config: {
    broadcast: { ack: true  },
    presence: { enabled: true },
    private: false,
  },
});

channel 
  .on(
    'broadcast',
    { event: '*' },
    (payload) => () => {
      console.log(payload);
    }
  )
  .subscribe(async (status) => {
    if (status !== 'SUBSCRIBED') return;

    await channel.track(user)

    await channel.send({
      type: 'broadcast',
      event: 'test',
      payload: { foo: 'bar' },
    });
  });

The test event (or any other event I send, is never received by the broadcast * event handler on other instances of the app (e.g. I open the app in 2 different tabs and authenticate with 2 different users). I've also tried replacing { event: '*' } with { event: 'test' } and it doesn't work either.

However, if I use the Realtime Inspector on Supabase and join the "test" channel, the messages are actually received there, and I can also see it being received in the network tab in DevTools.

I've tested this in localhost only so far.

Expected behavior

The broadcast event handler receives messages sent from other instances.

System information

• OS: Windows
• Browser: Chrome
• Version of supabase-js: 2.86.0
• Version of Node.js: v22.17.0

Library affected

supabase-js

Reproduction

No response

Steps to reproduce

No response

System Info

System:
    OS: Linux 5.10 Ubuntu 22.04.4 LTS 22.04.4 LTS (Jammy Jellyfish)
    CPU: (20) x64 12th Gen Intel(R) Core(TM) i9-12900HK
    Memory: 28.53 GB / 31.20 GB
    Container: Yes
    Shell: 5.1.16 - /bin/bash
  Binaries:
    Node: 22.17.0 - /home/usr/.nvm/versions/node/v22.17.0/bin/node
    Yarn: 1.22.19 - /mnt/c/Program Files/nodejs/yarn
    npm: 11.5.1 - /home/usr/.nvm/versions/node/v22.17.0/bin/npm
    pnpm: 10.19.0 - /home/usr/.local/share/pnpm/pnpm
    bun: 1.1.17 - /home/usr/.bun/bin/bun
  npmPackages:
    @supabase/ssr: ^0.7.0 => 0.7.0 
    @supabase/supabase-js: ^2.86.0 => 2.86.0

Used Package Manager

pnpm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Supabase JS Library issue and not an issue with the Supabase platform. If it's a Supabase platform related bug, it should likely be reported to supabase/supabase instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.