Discussion for SSE extension syntax

We’re moving SSE support into an extension (so it was decreed by @1cg). This thread is to collect suggestions/feedback on the syntax that we use in the new code. I’m just getting started now, so please let me know if I’m missing anything, or if there’s something we should add. Now is the time 😃

I think we should keep it as close to the existing syntax as possible, which should make it easier to migrate to the new code. Here’s my first pass:

<div hx-ext="sse" sse-url="/my-first-event-source" sse-swap="message">
    INDIVIDUAL SUBSCRIPTION: I will be swapped whenever an unnamed message is received
</div>

<div hx-ext="sse" sse-url="/my-second-event-source" sse-swap="event1">
    INDIVIDUAL SUBSCRIPTION: I will be swapped whenever a message named "event1" is received
</div>

<div hx-ext="sse" sse-url="/my-third-event-source">
    SHARED SUBSCRIPTION:
    Nothing will happen to THIS div, but its children will listen to messages instead.

    <div hx-ext="sse" sse-swap="message">
        I will be swapped whenever an unnamed message is received
    </div>

    <div hx-ext="sse" sse-swap="event1">
        I will be swapped whenever a message named "event1" is received
    </div>

</div>

[1cg]

for configuration options, I don’t mind if extensions add their own to the standard object, so long as it is documented clearly

for events, I like triggering a real event, so long as it is backwards compatible

[1cg]

I like injecting htmx (or a wrapper around its internals, maybe an extension API object?) into the extension.