fix(material/bottom-sheet): focus first tabbable element by default (#30549)

Switches the bottom sheet to focusing the first tabbale element by default like we do in `MatDialog`.

Note that we had a comment saying that the previous behavior was intentional. That seems to be a leftover from #14534 where the underlying cause was that we were delaying focus until the animation is done. We now have better ways of handling it so the comment isn't relevant anymore.

Fixes #30483.

Author: crisbeto

src/material/bottom-sheet/bottom-sheet-config.ts

@@ -58,15 +58,12 @@ export class MatBottomSheetConfig<D = any> {
    */
   closeOnNavigation?: boolean = true;
 
-  // Note that this is set to 'dialog' by default, because while the a11y recommendations
-  // are to focus the first focusable element, doing so prevents screen readers from reading out the
-  // rest of the bottom sheet content.
   /**
    * Where the bottom sheet should focus on open.
    * @breaking-change 14.0.0 Remove boolean option from autoFocus. Use string or
    * AutoFocusTarget instead.
    */
-  autoFocus?: AutoFocusTarget | string | boolean = 'dialog';
+  autoFocus?: AutoFocusTarget | string | boolean = 'first-tabbable';
 
   /**
    * Whether the bottom sheet should restore focus to the

src/material/bottom-sheet/bottom-sheet-container.ts

@@ -137,17 +137,11 @@ export class MatBottomSheetContainer extends CdkDialogContainer implements OnDes
     const isEnter = animationName === ENTER_ANIMATION;
     const isExit = animationName === EXIT_ANIMATION;
 
-    if (isEnter) {
-      this._trapFocus();
-    }
-
     if (isEnter || isExit) {
       this._animationStateChanged.emit({
         toState: isEnter ? 'visible' : 'hidden',
         phase: isStart ? 'start' : 'done',
       });
     }
   }
-
-  protected override _captureInitialFocus(): void {}
 }

src/material/bottom-sheet/bottom-sheet.spec.ts

@@ -622,7 +622,7 @@ describe('MatBottomSheet', () => {
     beforeEach(() => document.body.appendChild(overlayContainerElement));
     afterEach(() => overlayContainerElement.remove());
 
-    it('should focus the bottom sheet container by default', fakeAsync(() => {
+    it('should focus the first tabbable element by default', fakeAsync(() => {
       bottomSheet.open(PizzaMsg, {
         viewContainerRef: testViewContainerRef,
       });
@@ -631,9 +631,7 @@ describe('MatBottomSheet', () => {
       flush();
       viewContainerFixture.detectChanges();
 
-      expect(document.activeElement!.tagName)
-        .withContext('Expected bottom sheet container to be focused.')
-        .toBe('MAT-BOTTOM-SHEET-CONTAINER');
+      expect(document.activeElement!.tagName).toBe('INPUT');
     }));
 
     it('should create a focus trap if autoFocus is disabled', fakeAsync(() => {
@@ -669,72 +667,62 @@ describe('MatBottomSheet', () => {
       },
     );
 
-    it(
-      'should focus the bottom sheet element on open when autoFocus is set to ' +
-        '"dialog" (the default)',
-      fakeAsync(() => {
-        bottomSheet.open(PizzaMsg, {
-          viewContainerRef: testViewContainerRef,
-        });
+    it('should focus the bottom sheet element on open when autoFocus is set to "dialog"', fakeAsync(() => {
+      bottomSheet.open(PizzaMsg, {
+        viewContainerRef: testViewContainerRef,
+        autoFocus: 'dialog',
+      });
 
-        viewContainerFixture.detectChanges();
-        flush();
-        viewContainerFixture.detectChanges();
+      viewContainerFixture.detectChanges();
+      flush();
+      viewContainerFixture.detectChanges();
 
-        let container = overlayContainerElement.querySelector(
-          '.mat-bottom-sheet-container',
-        ) as HTMLInputElement;
+      let container = overlayContainerElement.querySelector(
+        '.mat-bottom-sheet-container',
+      ) as HTMLInputElement;
 
-        expect(document.activeElement)
-          .withContext('Expected container to be focused on open')
-          .toBe(container);
-      }),
-    );
+      expect(document.activeElement)
+        .withContext('Expected container to be focused on open')
+        .toBe(container);
+    }));
 
-    it(
-      'should focus the bottom sheet element on open when autoFocus is set to ' + '"first-heading"',
-      fakeAsync(() => {
-        bottomSheet.open(ContentElementDialog, {
-          viewContainerRef: testViewContainerRef,
-          autoFocus: 'first-heading',
-        });
+    it('should focus the bottom sheet element on open when autoFocus is set to "first-heading"', fakeAsync(() => {
+      bottomSheet.open(ContentElementDialog, {
+        viewContainerRef: testViewContainerRef,
+        autoFocus: 'first-heading',
+      });
 
-        viewContainerFixture.detectChanges();
-        flush();
-        viewContainerFixture.detectChanges();
+      viewContainerFixture.detectChanges();
+      flush();
+      viewContainerFixture.detectChanges();
 
-        let firstHeader = overlayContainerElement.querySelector(
-          'h1[tabindex="-1"]',
-        ) as HTMLInputElement;
+      let firstHeader = overlayContainerElement.querySelector(
+        'h1[tabindex="-1"]',
+      ) as HTMLInputElement;
 
-        expect(document.activeElement)
-          .withContext('Expected first header to be focused on open')
-          .toBe(firstHeader);
-      }),
-    );
+      expect(document.activeElement)
+        .withContext('Expected first header to be focused on open')
+        .toBe(firstHeader);
+    }));
 
-    it(
-      'should focus the first element that matches the css selector on open when ' +
-        'autoFocus is set to a css selector',
-      fakeAsync(() => {
-        bottomSheet.open(ContentElementDialog, {
-          viewContainerRef: testViewContainerRef,
-          autoFocus: 'p',
-        });
+    it('should focus the first element that matches the css selector on open when autoFocus is set to a css selector', fakeAsync(() => {
+      bottomSheet.open(ContentElementDialog, {
+        viewContainerRef: testViewContainerRef,
+        autoFocus: 'p',
+      });
 
-        viewContainerFixture.detectChanges();
-        flush();
-        viewContainerFixture.detectChanges();
+      viewContainerFixture.detectChanges();
+      flush();
+      viewContainerFixture.detectChanges();
 
-        let firstParagraph = overlayContainerElement.querySelector(
-          'p[tabindex="-1"]',
-        ) as HTMLInputElement;
+      let firstParagraph = overlayContainerElement.querySelector(
+        'p[tabindex="-1"]',
+      ) as HTMLInputElement;
 
-        expect(document.activeElement)
-          .withContext('Expected first paragraph to be focused on open')
-          .toBe(firstParagraph);
-      }),
-    );
+      expect(document.activeElement)
+        .withContext('Expected first paragraph to be focused on open')
+        .toBe(firstParagraph);
+    }));
 
     it('should re-focus trigger element when bottom sheet closes', fakeAsync(() => {
       const button = document.createElement('button');

tools/public_api_guard/material/bottom-sheet.md

@@ -81,8 +81,6 @@ export class MatBottomSheetContainer extends CdkDialogContainer implements OnDes
         toState: "visible" | "hidden";
         phase: "start" | "done";
     }>;
-    // (undocumented)
-    protected _captureInitialFocus(): void;
     enter(): void;
     exit(): void;
     // (undocumented)