* fix: Miscellaneous improvements for screenreader support.
* fix: Include field name in ARIA label.
* fix: Update block ARIA labels when inputs are shown/hidden.
* fix: Make field row label generation more robust.
## The basics
- [x] I [validated my changes](https://developers.google.com/blockly/guides/contribute/core#making_and_verifying_a_change)
## The details
### Resolves
Fixes#8206Fixes#8210Fixes#8213Fixes#8255Fixes#8211Fixes#8212Fixes#8254
Fixes part of #9301
Fixes part of #9304
### Proposed Changes
This PR completes the remaining ARIA roles and properties needed for all core fields. Specifically:
- #8206: A better name needed to be used for the checkbox value, plus there was an ARIA property missing for actually representing the checkbox state. The latter needed to be updated upon toggling the checkbox, as well. These changes bring checkbox fields in compliance with the ARIA checkbox pattern documented here: https://www.w3.org/WAI/ARIA/apg/patterns/checkbox/.
- #8210: This one required a lot of changes in order to adapt to the ARIA combobox pattern documented here: https://www.w3.org/WAI/ARIA/apg/patterns/combobox/. Specifically:
- Menus needed to have a unique ID that's also exposed in order to link the combobox element to its menu when open.
- ARIA's `activedescendant` proved very useful in ensuring that the current dropdown selection is correctly read when the combobox has focus but its menu isn't opened.
- The default properties available for options (label and value) aren't very good for readout, so a custom ARIA property was added for much clearer option readouts. This is only demonstrated for the math arithmetic block for now.
- The text element is normally hidden for ARIA but it's useful in conjunction with `activedescendant` to represent the current value selection.
- Images have been handled here as well (partly as part of #8255) by leveraging their alt text for readouts. This actually seems to work quite well both for current value and selection.
- #8213: Much of the improvements here come from the combobox (`FieldDropdown`) improvements explained above. However one additional bit was done to provide an explicit 'Variable <name>' readout for the purpose of clarity. This demonstrates some contextualization of the value of the field which may be a generally useful pattern to copy in other field contexts.
- #8255: Image fields have been refined since they were redundantly specifying 'image' when an `image` ARIA role is already being used. Now only the alt text is supplied along with the role context. Note that images need special handling since they can sometimes be navigable (such as when they have click handlers).
- #8211: Text input fields have had their labeling improved like all other fields, and the field's value is now exposed via its `text` element since this will show up as a `StaticText` node in the accessibility tree and automatically be read as part of the field's value.
- #8212: This gets the same benefits as the previous point since those improvements were included for both text and number input. However, existing `valuemin` and `valuemax` ARIA properties have been removed. It seems these are really only useful when introducing a slider mechanism (see https://www.w3.org/WAI/ARIA/apg/patterns/slider/) and from testing seems to not really be utilized for the basic text input that `FieldNumber` currently uses. It may be the case that this is a better pattern to use in the future, but it's more likely that other custom fields could benefit from more specific patterns like slider rather than `FieldNumber` being changed in that way.
- #8254 and part of #9304: Field labels have been completely removed from the accessibility node tree since they can never be navigated to (as #8254 explains all labels will be included as part of the block's ARIA label itself for readout parity with navigation options).
Note that it doesn't cover external fields (such as those supplied in blockly-samples), nor does it fully set up the infrastructure work for those. Ultimately that work needs to happen as part of #9301.
Beyond the role work above, this PR also introduces some fundamental work for #9301. Specifically:
- It demonstrates how block definitions could be used to introduce accessibility label customizations (in this case for the options of the arithmetic operator block's drop-down field, plus the block itself).
- It sets up some central label computation for all fields, though more thought is needed on whether this is sufficient for custom fields outside of core Blockly and on how to properly contextualize labels for field values. Core Blockly's fields are fairly simple for representing values which is why that aspect of #9301 didn't need to be solved in this PR. Note that the field labeling here is being used to improve all of the fields above, but also it tries to aggressively fall back to the _next best_ label to be used (though it's possible to run out of options which is why fields still need contextually-specific fallbacks).
### Reason for Changes
Generally the initial approach for implementing labels is leveraging as specific ARIA roles as exist to directly represent the element. This PR is completing that work for all of core Blockly's built-in fields, and laying some of the groundwork for generalizing this support for custom fields.
Having specific roles does potentially introduce inconsistencies across screen readers (though should improve consistency across sites for a single screen reader), and expectations for behaviors (like shortcuts) that may need to be ignored or only partially supported (#9313 is discussing this).
### Test Coverage
Only manual testing has been completed since this is experimental work.
Video demonstrating most of the changes:
[Screen recording 2025-10-01 4.05.35 PM.webm](https://github.com/user-attachments/assets/c7961caa-eae0-4585-8fd9-87d7cbe65988)
### Documentation
N/A -- Experimental work.
### Additional Information
This has only been tested on ChromeVox.
## The basics
- [x] I [validated my changes](https://developers.google.com/blockly/guides/contribute/core#making_and_verifying_a_change)
## The details
### Resolves
Fixes part of #8207
Fixes part of #3370
### Proposed Changes
This introduces initial broad ARIA integration in order to enable at least basic screen reader support when using keyboard navigation.
Largely this involves introducing ARIA roles and labels in a bunch of places, sometimes done in a way to override normal built-in behaviors of the accessibility node tree in order to get a richer first-class output for Blockly (such as for blocks and workspaces).
### Reason for Changes
ARIA is the fundamental basis for configuring how focusable nodes in Blockly are represented to the user when using a screen reader. As such, all focusable nodes requires labels and roles in order to correctly communicate their contexts.
The specific approach taken in this PR is to simply add labels and roles to all nodes where obvious with some extra work done for `WorkspaceSvg` and `BlockSvg` in order to represent blocks as a tree (since that seems to be the best fitting ARIA role per those available: https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Reference/Roles). The custom work specifically for blocks includes:
- Overriding the role description to be 'block' rather than 'tree item' (which is the default).
- Overriding the position, level, and number of sibling counts since those are normally determined based on the DOM tree and blocks are not laid out in the tree the same way they are visually or logically (so these computations were incorrect). This is also the reason for a bunch of extra computation logic being introduced.
One note on some of the labels being nonsensical (e.g. 'DoNotOverride?'): this was done intentionally to try and ensure _all_ focusable nodes (that can be focused) have labels, even when the specifics of what that label should be aren't yet clear. More components had these temporary labels until testing revealed how exactly they would behave from a screen reader perspective (at which point their roles and labels were updated as needed). The temporary labels act as an indicator when navigating through the UI, and some of the nodes can't easily be reached (for reasons) and thus may never actually need a label. More work is needed in understanding both what components need labels and what those labels should be, but that will be done beyond this PR.
### Test Coverage
No tests are added to this as it's experimental and not a final implementation.
The keyboard navigation tests are failing due to a visibility expansion of `connectionCandidate` in `BlockDragStrategy`. There's no way to avoid this breakage, unfortunately. Instead, this PR will be merged and then https://github.com/google/blockly-keyboard-experimentation/pull/684 will be finalized and merged to fix it. There's some additional work that will happen both in that branch and in a later PR in core Blockly to integrate the two experimentation branches as part of #9283 so that CI passes correctly for both branches.
### Documentation
No documentation is needed at this time.
### Additional Information
This work is experimental and is meant to serve two purposes:
- Provide a foundation for testing and iterating the core screen reader experience in Blockly.
- Provide a reference point for designing a long-term solution that accounts for all requirements collected during user testing.
This code should never be merged into `develop` as it stands. Instead, it will be redesigned with maintainability, testing, and correctness in mind at a future date (see https://github.com/google/blockly-keyboard-experimentation/discussions/673).
* feat: Add interfaces for keyboard navigation.
* feat: Add the Navigator.
* feat: Make core types conform to INavigable.
* feat: Require FlyoutItems elements to be INavigable.
* feat: Add navigation policies for built-in types.
* refactor: Convert Marker and LineCursor to operate on INavigables instead of ASTNodes.
* chore: Delete dead code in ASTNode.
* fix: Fix the tests.
* chore: Assuage the linter.
* fix: Fix advanced build/tests.
* chore: Restore ASTNode tests.
* refactor: Move isNavigable() validation into Navigator.
* refactor: Exercise navigation instead of ASTNode.
* chore: Rename astnode_test.js to navigation_test.js.
* chore: Enable the navigation tests.
* fix: Fix bug when retrieving the first child of an empty workspace.
* Feature: Add a setOptions method to field_dropdown
* add test for changing droopdown options
* split out setOptions tests into their own test suite
* Add additional tests
* auto format files
* refactor: Move functions into FieldDropdown.
* refactor: Make dropdown field image metrics static.
* refactor: Use template literals in FieldDropdown validator.
* chore(deps): Add pretter-plugin-organize-imports
* chore: Remove insignificant blank lines in import sections
Since prettier-plugin-organize-imports sorts imports within
sections separated by blank lines, but preserves the section
divisions, remove any blank lines that are not dividing imports
into meaningful sections.
Do not remove blank lines separating side-effect-only imports
from main imports.
* chore: Remove unneded eslint-disable directives
* chore: Organise imports
* fix: updated field_dropdown to properly infer its Field type with TS 5.3.3
* fix: removed undefined as an option as its not needed for the type fix
* fix: updated field_dropdown to allow |undefined class validation
* fix(build): Restore erroneously-deleted filter function
This was deleted in PR #7406 as it was mainly being used to
filter core/ vs. test/mocha/ deps into separate deps files -
but it turns out also to be used for filtering error
messages too. Oops.
* refactor(tests): Migrate advanced compilation test to ES Modules
* refactor(build): Migrate main.js to TypeScript
This turns out to be pretty straight forward, even if it would
cause crashing if one actually tried to import this module
instead of just feeding it to Closure Compiler.
* chore(build): Remove goog.declareModuleId calls
Replace goog.declareModuleId calls with a comment recording the
former module ID for posterity (or at least until we decide
how to reformat the renamings file.
* chore(tests): Delete closure/goog/*
For the moment we still need something to serve as base.js for
the benefit of closure-make-deps, so we keep a vestigial
base.js around, containing only the @provideGoog declaration.
* refactor(build): Remove vestigial base.js
By changing slightly the command line arguments to
closure-make-deps and closure-calculate-chunks the need to have
any base.js is eliminated.
* chore: Typo fix for PR #7415
We introduced the SKIP_SETUP sentinel value when converting
Field and its subclasses to ES6 class syntax, because super
must be called before any other code in a subclass
constructor, breaking the previous mechanism where subclasses
would set some properties before calling their superclass
constructor.
SKIP_SETUP was a singleton value of class Sentinel.
Recently, in PR #6639 @btw17 introduced the isSentinel type
predicate to improve the typing of Field. Unfortunately, there
were some aspects of this change that were not very elegant:
- isSentinel was declared as a static method on Field (rather
than on Sentinel itself).
- It only checks against the specific value SKIP_SETUP,
rather than checking if the argument is instanceof Sentinel
(though perhaps this is for efficiency?)
Additionally - as a result of the migration from ES6 to TS, and
predating PR #6639 - The signature for the Field constructor's
first argument was typed T|Sentinel, with subclass constructors
generally being <some type(s)>|Sentinel.
This creates a small problem when attempting to port Fields from
core to plugins, because Sentinel is not reexported by
core/utils.ts (and therefore not from core/blockly.ts either).
The latter problem could be solved simply by reexporting Sentinel,
or by having plugin constructors not accept SKIP_SETUP (though
this potentially makes them more difficult to subclass), but
neither is particularly desirable.
Instead, this PR proposes that we:
- Make Field.SKIP_SETUP a (unique) Symbol.
- Change the value argument to the Field constructor to accept
T|typeof Field.SKIP_SETUP - where typeof Field.SKIP_SETUP is
(like a literal type) a type that accepts just the single
value SKIP_SETUP.
- Remove the Sentinel class and core/utils/sentinel.ts.
Not treating this as a breaking change:
- Removes Field.isSentinel - though this addition has not yet
been published, so it can only break our own as-yet-unreleased
code in samples.
- Changes the type of Field.SKIP_SETUP and the first argument
of the Field constructor from Sentinel to typeof SKIP_SETUP
(a unique Symbol) - but given that Sentinel has never been
exported this should not break any actual external code.
* Reduce usage of obsolete .keyCode property.
* Rename private properties/methods which violate eslint rules.
* Use arrays of bound events rather than individual properties.
* Improve typing info.
* Also fix O(n^2) recursive performance issue in theme's getComponentStyle function.
* And replace String(...) with '${...}' (smaller, faster).
* .toString() is considered harmful.
* chore: replace `AnyDuringMigration` for field value functions
* chore: removed unnecessary `KeyboardEvent` comments and `AnyDuringMigration` casts
* chore: cleaned up `doValueUpdate_` and `doClassValidation_` in `Field` subclasses
* fix: updated `FieldValidator` to allow returning `undefined` and restructured `setValue`
* fix: implemented initial `core/field_checkbox.ts` feedback
* fix: updated `Field` to accept `U` and `undefined` and reverted subclass constructor handling of the input value
* fix: reverted `getVars` to returning `string[]` and added related comment
* chore: removed unnecessary comment
* fix: updated `processValidation_` to no longer allow returning `undefined`
* fix: removed `Un` type alias for `undefined`
* chore: removed unnecessary string cast in `core/field_colour.ts`
* fix: updated `doClassValidation_` not to expect `null` since it will never come up in `setValue`
* fix: updated `doClassValidation_` to only allow `undefined` when the new value exists
* Updated `FieldValidator` type to expect `newValue` to exist
* cleanup: updated `picker` from type `Element` to type `HTMLElement`
* fix: updated `doValueInvalid_` type info in `core/field_input.ts` to handle `string` and `undefined`
* fix: reverted `getValue` in `core/field_checkbox.ts` to previous logic
* fix: updated the `Field` constructor to allow `value` to be optional
* chore: consolidated `Validation` with `FieldValidator` and `doClassValidation_`
* fix: reverted generic param `U` while handling diverging user input is being discussed
* fix: updated `doClassValidation_` return comment to work for TSDoc
* fix: misc keyboard event function tweaks
* chore: add validator and field value types
* chore/clean up unused default and unnecessary field type setting
* chore: removed IRegisterableField and updated various Field instances
* fix: remove unused field image validator function
* chore: added pass-through constructor to field_textinput
* chore: added generator type to `core/field_dropdown.ts` and updated affected files
* chore: added type to ARROW_CHAR in `core/field_dropdown.ts`
* chore: cleaned up misc 'AnyDuringMigration' cases and related comments
* fix: misc adjustments from PR feedback
* Fix: simplified `getOptions`
* fix: removed outdated arrow and cleaned up formatting
* fix: cleanup format after rebase
* fix: make getSourceBlock nullable again
* chore: format
* chore: move to a specific error
* chore: also update procedures with new error
* chore: format
* chore: cleaned up several type cases in core/field.ts and impacted files
* chore: updated instances of `sourceBlock_!` to `getSourceBlock()`
* chore: updated instances of `fieldGroup_!` to `getSvgRoot()`
* chore: updated nullable variables in `field.ts` to use internal functions
* chore: updated getSourceBlock and getSvgRoot to handle nullability
* chore: updated comments to reference throwing an error
* fix: reverted `getSvgRoot` to `fieldGroup_` in null-accepting areas
* fix: updated `getSvgRoot` to allow null and added null handling methods
* fix: moved click target error handling to their specific cases
* fix: updated drawer.ts to handle cast svg group to defined
