Behavior of the onfetch setter regarding no-fetch service workers

[catalinb]

With the changes discussed in #718 addEventListener should throw unless called during the script's initial evaluation. What should be the behavior of setting the onfetch event handler?

I'm guessing it should throw as well, but this was not included in the spec.

from https://html.spec.whatwg.org/multipage/webappapis.html#event-handler-attributes

When an event handler H of an element or object T implementing the EventTarget interface is first set to a non-null value, the user agent must append an event listener to the list of event listeners associated with T with type set to the event handler event type corresponding to H and callback set to the event handler processing algorithm defined below.

This can be changed to use addEventListener for adding the event listener.

[annevk]

This should be fixed together with whatwg/dom#371.

[jungkees]

Thanks for spotting. I'll follow up on this after clarifying whatwg/dom#371.

[annevk]

What's the status here @jungkees? Would be good to sort this out.

[jungkees]

When an event handler H of an element or object T implementing the EventTarget interface is first set to a non-null value

Event handler IDL attributes, on setting, must set the corresponding event handler to their new value

Yeah, the idea is to add the following step to the above places:

"Throw when T is a ServiceWorkerGlobalScope object, type is an event type in the while list, and the SW's has ever been evaluated flag is set."

But this isn't decided yet. We should conclude what the better design would be in whatwg/dom#371.

[annevk]

Since nobody else took this up I wrote the necessary patches for DOM and HTML.

[annevk]

OP is now addressed, but I think we should leave this open until someone has addressed the questions I raised in whatwg/dom#371 and there's tests covering exactly what we want to be doing here.

[jungkees]

@annevk, thanks for helping out with this issue. I leave a comment here as the PRs have already been merged.

Through the discussion in whatwg/dom#371, we decided to confine the event target to ServiceWorkerGlobalScope instead of all the objects within the global scope. So, https://github.com/whatwg/dom/pull/596/files#diff-a467e681501e456ce8c1ef31425e1b41R1046 should be "If evenTarget is a ServiceWorkerGlobalScope object, ..".

[annevk]

Well, that issue isn't fixed yet and that decision is being contested by bz in that issue. That's why that text hasn't been touched thus far.

[annevk]

Also, are there any tests?

[jungkees]

That bit was posed by the OP: whatwg/dom#371 (comment). Allowing the event target to be any object doesn't make sense, and the proposed change is in the direction of a solution.

I'll need to check out for tests.

[annevk]

I think throwing in general doesn't make sense, even for the global object. As bz points out, you could have custom events that you might want to register at a later time.

[jungkees]

Closing via whatwg/html@9a2a66c, web-platform-tests/wpt@bc28ef5, and whatwg/dom#653.