fix(select): improve screen reader announcement timing for validation errors (#30723)

Issue number: internal

---------

<!-- Please do not submit updates to dependencies unless it fixes an
issue. -->

<!-- Please try to limit your pull request to one type (bugfix, feature,
etc). Submit multiple pull requests if needed. -->

## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

Currently, when an error text is shown, it may not announce itself to
voice assistants. This is because the way error text currently works is
by always existing in the DOM, but being hidden when there is no error.
When the error state changes, the error text is shown, but as far as the
voice assistant can tell it's always been there and nothing has changed.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- Updated aria attributes
- Added observer with an observer

We had to do this with a mutation observer and state because it's
important in some frameworks, like Angular, that state changes to cause
a re-render. This, combined with some minor aria changes, makes it so
that when a field is declared invalid, it immediately announces the
invalid state instead of waiting for the user to go back to the invalid
field.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

<!--
  If this introduces a breaking change:
1. Describe the impact and migration path for existing applications
below.
  2. Update the BREAKING.md file with the breaking change.
3. Add "BREAKING CHANGE: [...]" to the commit description when merging.
See
https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#footer
for more information.
-->


## Other information

<!-- Any other information that is important to this PR such as
screenshots of how the component looks before and after the change. -->


[Preview](https://ionic-framework-git-fw-6797-ionic1.vercel.app/src/components/select/test/validation/)

core/src/components/select/select.tsx

@@ -1,7 +1,7 @@
 import type { ComponentInterface, EventEmitter } from '@stencil/core';
-import { Component, Element, Event, Host, Method, Prop, State, Watch, h, forceUpdate } from '@stencil/core';
+import { Build, Component, Element, Event, Host, Method, Prop, State, Watch, h, forceUpdate } from '@stencil/core';
 import type { NotchController } from '@utils/forms';
-import { compareOptions, createNotchController, isOptionSelected } from '@utils/forms';
+import { compareOptions, createNotchController, isOptionSelected, checkInvalidState } from '@utils/forms';
 import { focusVisibleElement, renderHiddenInput, inheritAttributes } from '@utils/helpers';
 import type { Attributes } from '@utils/helpers';
 import { printIonWarning } from '@utils/logging';
@@ -64,6 +64,7 @@ export class Select implements ComponentInterface {
   private inheritedAttributes: Attributes = {};
   private nativeWrapperEl: HTMLElement | undefined;
   private notchSpacerEl: HTMLElement | undefined;
+  private validationObserver?: MutationObserver;
 
   private notchController?: NotchController;
 
@@ -81,6 +82,13 @@ export class Select implements ComponentInterface {
    */
   @State() hasFocus = false;
 
+  /**
+   * Track validation state for proper aria-live announcements.
+   */
+  @State() isInvalid = false;
+
+  @State() private hintTextID?: string;
+
   /**
    * The text to display on the cancel button.
    */
@@ -298,10 +306,51 @@ export class Select implements ComponentInterface {
        */
       forceUpdate(this);
     });
+
+    // Watch for class changes to update validation state.
+    if (Build.isBrowser && typeof MutationObserver !== 'undefined') {
+      this.validationObserver = new MutationObserver(() => {
+        const newIsInvalid = checkInvalidState(this.el);
+        if (this.isInvalid !== newIsInvalid) {
+          this.isInvalid = newIsInvalid;
+          /**
+           * Screen readers tend to announce changes
+           * to `aria-describedby` when the attribute
+           * is changed during a blur event for a
+           * native form control.
+           * However, the announcement can be spotty
+           * when using a non-native form control
+           * and `forceUpdate()`.
+           * This is due to `forceUpdate()` internally
+           * rescheduling the DOM update to a lower
+           * priority queue regardless if it's called
+           * inside a Promise or not, thus causing
+           * the screen reader to potentially miss the
+           * change.
+           * By using a State variable inside a Promise,
+           * it guarantees a re-render immediately at
+           * a higher priority.
+           */
+          Promise.resolve().then(() => {
+            this.hintTextID = this.getHintTextID();
+          });
+        }
+      });
+
+      this.validationObserver.observe(el, {
+        attributes: true,
+        attributeFilter: ['class'],
+      });
+    }
+
+    // Always set initial state
+    this.isInvalid = checkInvalidState(this.el);
   }
 
   componentWillLoad() {
     this.inheritedAttributes = inheritAttributes(this.el, ['aria-label']);
+
+    this.hintTextID = this.getHintTextID();
   }
 
   componentDidLoad() {
@@ -328,6 +377,12 @@ export class Select implements ComponentInterface {
       this.notchController.destroy();
       this.notchController = undefined;
     }
+
+    // Clean up validation observer to prevent memory leaks.
+    if (this.validationObserver) {
+      this.validationObserver.disconnect();
+      this.validationObserver = undefined;
+    }
   }
 
   /**
@@ -1056,8 +1111,8 @@ export class Select implements ComponentInterface {
         aria-label={this.ariaLabel}
         aria-haspopup="dialog"
         aria-expanded={`${isExpanded}`}
-        aria-describedby={this.getHintTextID()}
-        aria-invalid={this.getHintTextID() === this.errorTextId}
+        aria-describedby={this.hintTextID}
+        aria-invalid={this.isInvalid ? 'true' : undefined}
         aria-required={`${required}`}
         onFocus={this.onFocus}
         onBlur={this.onBlur}
@@ -1067,9 +1122,9 @@ export class Select implements ComponentInterface {
   }
 
   private getHintTextID(): string | undefined {
-    const { el, helperText, errorText, helperTextId, errorTextId } = this;
+    const { helperText, errorText, helperTextId, errorTextId, isInvalid } = this;
 
-    if (el.classList.contains('ion-touched') && el.classList.contains('ion-invalid') && errorText) {
+    if (isInvalid && errorText) {
       return errorTextId;
     }
 
@@ -1084,14 +1139,14 @@ export class Select implements ComponentInterface {
    * Renders the helper text or error text values
    */
   private renderHintText() {
-    const { helperText, errorText, helperTextId, errorTextId } = this;
+    const { helperText, errorText, helperTextId, errorTextId, isInvalid } = this;
 
     return [
-      <div id={helperTextId} class="helper-text" part="supporting-text helper-text">
-        {helperText}
+      <div id={helperTextId} class="helper-text" part="supporting-text helper-text" aria-live="polite">
+        {!isInvalid ? helperText : null}
       </div>,
-      <div id={errorTextId} class="error-text" part="supporting-text error-text">
-        {errorText}
+      <div id={errorTextId} class="error-text" part="supporting-text error-text" role="alert">
+        {isInvalid ? errorText : null}
       </div>,
     ];
   }