Missing ErrorEvent

[jimmywarting]

What is the problem this feature will solve?

Where trying to construct a new ErrorEvent... but it was defined.

What is the feature you are proposing to solve the problem?

A few web features can dispatch a ErrorEvent like web workers...

What alternatives have you considered?

No response

[bnoordhuis]

Node doesn't emit ErrorEvents itself so it's questionable if it makes sense to add it.

But... without working code it won't happen in the first place. Go ahead and open a pull request and see how it's received.

[jimmywarting]

As a effort into implementing spec'ed web worker (#43583) (which is highly desirable and upvoted) then the worker.onerror would have to emit a ErrorEvent.

I notice this when i tried to build a more spec comp. web worker.

[jimmywarting]

I have notice other events that Deno also has... here is a list of them: https://github.com/jimmywarting/missing-dom-events#compatibility-table

• CloseEvent: For when a WebbSocket closes.
• ErrorEvent: For when WebSocket fails and you also get this on globalThis.onerror

anyway undici have both of this event builtin, maybe it could just be a mater of just exposing those on the global scope?

---

There is also a desire to make globalThis inherit EventTarget in some open issue here too. so it can dispatch/emit postMessages, ErrorEvents

[github-actions]

There has been no activity on this feature request for 5 months and it is unlikely to be implemented. It will be closed 6 months after the last non-automated comment.

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[regseb]

• CloseEvent: For when a WebbSocket closes.
• ErrorEvent: For when WebSocket fails and you also get this on globalThis.onerror

ErrorEvent isn't used by WebSocket. The error event of WebSocket returns a generic Event. Maybe only web workers use ErrorEvent.

Now that WebSocket is in Node.js v21 (behind the --experimental-websocket flag), I've opened an issue #50275 to add CloseEvent in Node.js.

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[KhafraDev]

WebSocket may use ErrorEvents, see the spec: https://html.spec.whatwg.org/multipage/indices.html#event-error

[regseb]

@KhafraDev The https://html.spec.whatwg.org/multipage/indices.html#event-error page describes the general HTML specification. The word WebSocket doesn't appear. For the error event, it indicates that the type may be Event or ErrorEvent.

The MDN page WebSocket: error event indicates only A generic Event.

The WebSocket specification doesn't mention ErrorEvent. For events, it doesn't specify the type of error events, whereas for the close event, it's a CloseEvent:

• fire an event named error at the WebSocket object.
• Fire an event named close at the WebSocket object, using CloseEvent,

web-platform-tests only tests Event for error:

• assert_true(e instanceof Event)
• assert_equals(e.toString(), '[object Event]', "error e.toString()")
• assert_true(e instanceof Event).

If I run the following code in Firefox or Chromium, e is an Event variable.

new WebSocket("ws://localhost:666").addEventListener("error", (e) => console.log(e, e.constructor.name));

[github-actions]

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