Relevant global object

[annevk]

I wonder about two things:

1. Is this global object immutable? (I suspect that Firefox mutates it per https://www.w3.org/Bugs/Public/show_bug.cgi?id=20567 as otherwise Firefox would continue leaking globals, but are there other such cases and do other browsers ever do it?)
2. For a node, do we ever not want the relevant global object of its node document, rather than the node itself? (This depends in part on 1. Browsers that don't change the global when moving nodes around, probably don't want to use the node's global, but rather it's node document's global. I observed this at least for window.event: Extra window.event tests web-platform-tests/wpt#10329.)

cc @bzbarsky @domenic

[annevk]

(My window.event debugging appears to be wrong.)

[bzbarsky]

Is this global object immutable?

Per spec, no. https://heycam.github.io/webidl/#es-platform-objects explicitly says:

The global environment that a given platform object is associated with can change
after it has been created.

And yes, Firefox does change it on adopt.

For a node, do we ever not want the relevant global object of its node document, rather than the node itself?

Mmm. Good question; I hadn't thought about this before because in Firefox the two are always the same. We would probably need to audit all uses of relevant global on nodes and see what they're really after...

[domenic]

I'm not sure how to approach this issue, as it appears to be all Firefox-specific concerns.

[bzbarsky]

Concern 2 is only a concern for non-Firefox browers, no?

[guest271314]

Can "Relevant global object", "node's global" and "node document's global" be clearly defined, here? What are the distinctions between the three terms? How to determine and verify each case?

[guest271314]

Is window.event value expected to be an event programmatically dispatched to an node where the document which contains the node is, for example a document loaded from an XMLHttpRequest()?

[bzbarsky]

Can "Relevant global object", "node's global" and "node document's global" be clearly defined, here?

See https://html.spec.whatwg.org/multipage/webappapis.html#relevant

"node's global" and "node document's global" are shorthand for "the relevant global object of the node" and "the relevant global object of the node's node document", in the https://dom.spec.whatwg.org/#concept-node-document sense.

How to determine and verify each case?

I'm not sure what you're asking. For purposes of this issue, what probably needs to happen is identifying all APIs exposed on nodes that use the "relevant global" concept, testing each one with a node that has a different-global node document, and seeing what browsers do in practice in terms of which global they use.

[guest271314]

Not yet gathering the full scope of the inquiry. This is what tried so far

      let doc;
      const request = new XMLHttpRequest();
      request.responseType = "document";
      request.onload = e => {
        doc = request.response;
        doc.onclick = e => console.log(e, window.event);
        console.log(window.event, doc.activeElement);
        doc.documentElement.click();
      }
      request.onerror = e => console.log(e);
      request.open("GET", "document.html", true);
      request.send();

Trying to get top.event or parent.event at plnkr throws CORS error. Have not yet tried to create a test where the parent window.event is logged when the event is dispatched at #document loaded from XMLHttpRequest() and no element of that #document is appended to a displayed document.

[bzbarsky]

The relevant global of everything in your testcase is the same. The testcase of interest that involves window.event is more like this:

<iframe></iframe>
<script>
  var body = frames[0].document.body;
  document.documentElement.appendChild(body);
  // During dispatch of the event below, is .event set on _this_ window
  // or the window in the subframe?  The former is the global of the node
  // document; the latter is the global of the node in some browsers.
  body.dispatchEvent(new Event("test"));
</script>

But the bigger question is what should happen for all APIs on nodes that use the relevant global.