Feature Policy: focus-without-user-activation

[siliu1]

focus-without-user-activation is a new feature policy that can be used to block programmatic focus changes that are not triggered through user activation (explainer).

The motivation behind this feature policy is to provide better security for websites that embed third party contexts.

This change makes modifications to the following focus API:

• autofocus
• element.focus(options)
• window.focus()

The WHATWG resolved to add a new feature policy, focus-without-user-activation, to control whether third-party iframes can take focus programmatically. (w3c/webappsec-permissions-policy#273 (comment))

The original PR contains all prior discussions regarding the feature policy. However, since I don't have editor access to it, I've created this new PR.

• At least two implementers are interested (and none opposed):
  • Chromium.
  • Gecko: focus-without-user-activation feature policy mozilla/standards-positions#1080
  • WebKit: focus-without-user-activation feature policy WebKit/standards-positions#406
• Tests are written and can be reviewed and commented upon at:
  • wpt/feature-policy/experimental-features/focus-without-user-activation-disabled-tentative.html
  • wpt/feature-policy/experimental-features/focus-without-user-activation-enabled-tentative.sub.html
• Implementation bugs are filed:
  • Chromium: https://issues.chromium.org/issues/371112534
  • Gecko: TBA
  • WebKit: TBA
• MDN issue is filed: …
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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/acknowledgements.html ( diff )
/infrastructure.html ( diff )
/interaction.html ( diff )
/interactive-elements.html ( diff )
/popover.html ( diff )

[zcorpan]

There are more APIs that call the focusing steps. For example showModal() on dialog. See https://html.spec.whatwg.org/multipage/interaction.html#focusing-steps (click on "focusing steps" to see callers).

[siliu1]

There are more APIs that call the focusing steps. For example showModal() on dialog. See https://html.spec.whatwg.org/multipage/interaction.html#focusing-steps (click on "focusing steps" to see callers).

This is a good catch. I added extra steps in dialog focusing steps and popover focusing steps to respect the new focus-without-user-activation policy.