Update FocusEvent pages

[danburzo]

Summary

I've made the following updates:

• Note that focusin/focusout follow their non-bubbling counterparts;
• Note that focusin/focusout don't (yet) have an event handling property;
• Add the description of the FocusEvent.relatedTarget property on all events;
• Link to HTMLElement.focus() / .blur() methods from the similarly-named event pages.
• Adds a section to FocusEvent that describes the difference in the order of events between the spec and current browser implementations, and points to it from the focusin/focusout pages.

Fixes #14084.

Motivation

I propose these changes to make the FocusEvent pages more useful to readers by matching what they will experience in browsers.

Supporting details

• UIEvents spec: focus event order
• Figure out what to do with focusin/focusout w3c/uievents#88
• Define all focus events whatwg/html#3514
• Should onfocusin/onfocusout IDL attributes be added? whatwg/html#4542

Related issues

Fixes #14084.

Metadata

• Adds a new document
• Rewrites (or significantly expands) a document
• Fixes a typo, bug, or other error

[github-actions]

Preview URLs (7 pages)

• /en-US/docs/Web/API/Element/blur_event
• /en-US/docs/Web/API/Element/focus_event
• /en-US/docs/Web/API/Element/focusin_event
• /en-US/docs/Web/API/Element/focusout_event
• /en-US/docs/Web/API/Element
• /en-US/docs/Web/API/FocusEvent
• /en-US/docs/Web/API/HTMLElement/focus

Flaws (7)

Note! 6 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/API/Element
Title: Element
Flaw count: 7

• macros:
  • /en-US/docs/Web/API/Element/getBoxQuads does not exist
  • /en-US/docs/Web/API/Element/select_event redirects to /en-US/docs/Web/API/HTMLInputElement/select_event
  • /en-US/docs/Web/API/HTMLElement/oncopy redirects to /en-US/docs/Web/API/HTMLElement/copy_event
  • /en-US/docs/Web/API/HTMLElement/oncut redirects to /en-US/docs/Web/API/HTMLElement/cut_event
  • /en-US/docs/Web/API/HTMLElement/onpaste redirects to /en-US/docs/Web/API/HTMLElement/paste_event
• bad_bcd_links:
  • no explanation!
  • no explanation!

External URLs (2)

URL: /en-US/docs/Web/API/HTMLElement/focus
Title: HTMLElement.focus()

• https://blog.whatwg.org/focusing-on-focus (1 time)

---

URL: /en-US/docs/Web/API/FocusEvent
Title: FocusEvent

• https://w3c.github.io/uievents/ (1 time) (Note! This may be a new URL 👀)

(this comment was updated 2022-09-28 00:17:32.865423)

[Rumyra]

@danburzo from what I can see the changes suggested have been made - can you confirm?

If you resolve conflicts we should be able to get this pr through 👍

[danburzo]

@Rumyra I've adapted my proposed changes to the new structure for FocusEvent pages.

Substantial new things:

• The description for FocusEvent.relatedTarget is now specific to each event, but does not repeat the cases where relatedTarget might be null, which can be consulted on the property's page.
• I've removed mentions of the onfocusin / onfocusout event handling properties, which are not currently specced (see whatwg/html#4542)

[estelle]

@jpmedley Is this ok to merge?