[b4ckup]

This sounds like a good use case for using a service worker. All tabs talk to the service worker and the worker is the single instance that talks to the backend and can use only one connection. Maybe there are some trade offs for using SSE in web workers, I'm not sure.

[Keithamus]

BroadcastChannel is a better solution for a couple of reasons. Service Workers are better at intercepting network requests and returning items from a cache, there’s some amount of additional effort to do work outside of that. The other thing is they’re a little more difficult to set up. A broadcast channel can be handled in a couple lines of code, easily debuggable as they run on the main thread, and they’re more suited to the purpose.

[nchmy]

Weblocks (https://developer.mozilla.org/en-US/docs/Web/API/Web_Locks_A...) are an even better way to do this than Broadcast Channel

[b4ckup]

I disagree. You can just postMessage to communicate with the service worker and therefore I imagine the code using broadcast channel to be actually quite similar. About debugging, service workers are easily debuggable, though not on the main thread as you already mentioned.

[fitsumbelay]

agreed. Workers was one of my first thoughts but I think BroadcastChannel delivers with much lower LOE