Live reload doesn't refresh speaker notes in speaker view

[eliasp]

For editing/previewing my slides, I run npm start to make use of the live reload feature, to see changes on the fly.

While this works just fine for the slide content, it doesn't refresh the notes in the "Speaker View", although the slide previews in the "Speaker View" get refreshed just fine.
This happens for plain HTML notes, as well as for Markdown notes.

I can reproduce this issue in

• Mozilla Firefox 82.0/Win10 1909
• Google Chrome 86.0.4240.111/Win10 1909

Using reveal.js 0582f57 on Ubuntu 18.04 (NodeJS 12.18.4 provided through a Nix Shell environment)

Configuration:

Reveal.initialize({
    hash: true,
    plugins: [ RevealMarkdown, RevealNotes ],
    totalTime: 2100,
});

The output of gulp contains nothing unexpected:

[nix-shell:~/code-repositories/personal/eprobst/saltstack-a-history-of-systems]$ npm start

> reveal.js@4.1.0 start /home/eprobst/code-repositories/personal/eprobst/saltstack-a-history-of-systems
> gulp serve

[16:55:13] Using gulpfile ~/code-repositories/personal/eprobst/saltstack-a-history-of-systems/gulpfile.js
[16:55:13] Starting 'serve'...
[16:55:13] Starting server...
[16:55:13] Server started http://0.0.0.0:8000
[16:55:13] LiveReload started on port 35729
[16:55:13] Running server
[16:55:39] Starting 'reload'...
[16:55:40] Finished 'reload' after 82 ms
[16:55:46] Starting 'reload'...
[16:55:46] Finished 'reload' after 8.41 ms
[16:56:26] Starting 'reload'...
[16:56:26] Finished 'reload' after 16 ms
[16:56:30] Starting 'reload'...
[16:56:30] Finished 'reload' after 2.97 ms

[mikestopcontinues]

Same problem, using Vite to build/serve. After reload, not only do the notes not update, but the current notes stick. Only exiting and re-entering presenter modes shows the updates.

[dabrahams]

I'm having the same problem as @mikestopcontinues when running the presentation through Jekyll serve. This seems like something that oughta be easy to fix, but I'm at a loss.

[hakimel]

This has been fixed in master 🥳 Please give it a try when you get a chance.

The core issue here has always been the main window losing its reference to the speaker window after reloading. I've tried to fix this a few times before but finally found a solution today.

The speaker window now continuously sends a heartbeat via postMessage every 1s. The main window listens for these heartbeats and if it ever receives one from a notes window it has no reference to, it will reconnect that window. That means no matter why the main window reloads it will always reconnect to the open speaker view.

[mikestopcontinues]

Thanks @hakimel. You're solution actually also just solved a long-standing bug in my own app's iframe communication. :D