`document.all`, and that's only required for web browsers to implement - it's in Annex B. Some newer JS engines targeting non-browser platforms (like Moddable's XS and I believe Nashorn as well) don't even implement it, and it leads to a slightly simpler runtime.
And it's only there thanks to a bunch of people relying on `if (document.all) doSomething()` for detecting legacy crap while others at the same time just assuming it's there without checking for it first, almost always on ancient web pages. Oh, and people were also calling it via `document.all(nameOrIndex)` instead of `document.all[nameOrIndex]`, so the HTML spec also has it implementing `[[Call]]`. - HTML spec: https://html.spec.whatwg.org/multipage/common-dom-interfaces.html#the-htmlallcollection-interface - ES spec: https://tc39.es/ecma262/#sec-IsHTMLDDA-internal-slot In case you're wondering, I've never seen anyone return or store `document.all` ever. ----- Isiah Meadows cont...@isiahmeadows.com www.isiahmeadows.com On Sat, Jul 27, 2019 at 5:20 PM Michael Haufe <t...@thenewobjective.com> wrote: > > More than one case: > > > > <script> > > var foo = f() > > typeof foo // object > > foo instanceof Object // false > > > > var bar = g() > > typeof bar //undefined > > bar instanceof Object //true > > bar() // > > </script> > > > > You could probably guess what the value of foo is. Can you guess what the > second is in any useful way? > > > > From: Jordan Harband <ljh...@gmail.com> > Sent: Saturday, July 27, 2019 3:56 PM > To: Michael Haufe <t...@thenewobjective.com> > Cc: es-discuss@mozilla.org > Subject: Re: Proposal: Typeof Trap > > > > With something that while unintuitive in one case, is eternally robust and > reliable. > > > > If you want extensibility, define Symbol.toStringTag on your objects. > > > > On Sat, Jul 27, 2019 at 1:23 PM Michael Haufe <t...@thenewobjective.com> > wrote: > > If it's unfixably broken[1], non-extensible, excessively vague, and > non-orthogonal, where does that leave you? > > > > [1] <https://twitter.com/BrendanEich/status/798317702775324672> > > > > From: Jordan Harband <ljh...@gmail.com> > Sent: Saturday, July 27, 2019 3:00 PM > To: Michael Haufe <t...@thenewobjective.com> > Cc: ViliusCreator <viliuskubilius...@gmail.com>; es-discuss@mozilla.org > Subject: Re: Proposal: Typeof Trap > > > > Those two PRs are about removing implementation-defined behavior from > `typeof`, making it *more* reliable - there is no trend away from using and > relying on `typeof`, full stop. > > > > `Symbol.hasInstance` is a part of why `instanceof` is actually unreliable - > because user code can hook into it. It would be a massive loss imo if > `typeof` lost its bulletproof status by adding a user hook. > > > > On Sat, Jul 27, 2019 at 12:37 PM Michael Haufe <t...@thenewobjective.com> > wrote: > > The trend seems to be to rely on typeof less and less as time passes: > > > > From the March 2019 Agenda > <https://github.com/tc39/agendas/blob/274e49412c09f81a0a82f386e6eead481c69adad/2019/03.md>: > > > > “Implementation-defined typeof still necessary?” > <https://github.com/tc39/ecma262/issues/1440> > > “Normative: Remove implementation-defined typeof behavior” > <https://github.com/tc39/ecma262/pull/1441> > > > > > > The only real discussion around this I can find is from a related proposal > from Brendan Eich a few years ago: > > > > https://esdiscuss.org/topic/typeof-extensibility-building-on-my-value-objects-slides-from-thursday-s-tc39-meeting > > > > > > > > From: ViliusCreator <viliuskubilius...@gmail.com> > Sent: Saturday, July 27, 2019 2:04 PM > To: Michael Haufe <t...@thenewobjective.com> > Subject: RE: Proposal: Typeof Trap > > > > Yes, but it traps `typeof `, not `instanceof`. There’s difference there. > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
