Mdn states that;

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

@anonrig Thank you for checking. BTW, I have one question. mdn states that cancelBubble, returnValue, and srcElement are also deprecated, but as I know Event class has these properties for now. So do we need to remove these properties?

Refs: https://developer.mozilla.org/en-US/docs/Web/API/Event/cancelBubble
Refs: https://developer.mozilla.org/en-US/docs/Web/API/Event/returnValue
Refs: https://developer.mozilla.org/en-US/docs/Web/API/Event/srcElement

I believe it will be a breaking change. We should deprecate them, if it’s not, through documentation.

Thank you for feedback. I'll close this PR soon.

I actually disagree with @anonrig here. If the spec defines initEvent on EventTarget we have to implement it in order to be spec compliant.

And indeed we fail the relevant WPT tests.

Let's ask some WHATWG folk - @domenic @annevk should we implement initEvent (and other stuff tagged legacy) or is it fine not to?

Browsers definitely have to keep supporting it and I think what MDN states is stretching reality. It's probably easier for web developers if Node.js supports it as well so they don't have to adapt code, but I could see an argument for not implementing it.

@deokjinkim feel free to reopen then :)

@benjamingr Thank you for review. Added description of event.initEvent to doc. fa88cdb

I'm still not in favor of adding a deprecated API to Node.js without any request from a user, just for the goal of spec compliance.

With web standards I feel that you either implement the standard or you don't. This isn't an API like EventEmitter where we get to do as we please - with EventTarget I feel strongly that changes to the API need to be reflected by changes to the spec.

I can definitely see an argument for amending the WHATWG DOM spec (which project members have done in the past) to make initEvent optional (by adding it to an annex clients may implement or making it an extension e.g.).

CI: https://ci.nodejs.org/job/node-test-pull-request/48926/

Rebased this PR to fix conflict and squashed to 1 commit.

I couldn't find a past example of adding a deprecated API to Node.js.

We've added atob and btoa, marked as Legacy since their initial implementation in Node.js.

CI: https://ci.nodejs.org/job/node-test-pull-request/48995/

Landed in 2ff8c50

This is not landing cleanly in v18.x