feat(dialog): allow focus restoration to be disabled (#12519)

Author: crisbeto

src/lib/dialog/dialog-config.ts

@@ -95,6 +95,12 @@ export class MatDialogConfig<D = any> {
   /** Whether the dialog should focus the first focusable element on open. */
   autoFocus?: boolean = true;
 
+  /**
+   * Whether the dialog should restore focus to the
+   * previously-focused element, after it's closed.
+   */
+  restoreFocus?: boolean = true;
+
   /** Scroll strategy to be used for the dialog. */
   scrollStrategy?: ScrollStrategy;
 

src/lib/dialog/dialog-container.ts

@@ -148,7 +148,7 @@ export class MatDialogContainer extends BasePortalOutlet {
     const toFocus = this._elementFocusedBeforeDialogWasOpened;
 
     // We need the extra check, because IE can set the `activeElement` to null in some cases.
-    if (toFocus && typeof toFocus.focus === 'function') {
+    if (this._config.restoreFocus && toFocus && typeof toFocus.focus === 'function') {
       toFocus.focus();
     }
 

src/lib/dialog/dialog.spec.ts

@@ -1009,6 +1009,37 @@ describe('MatDialog', () => {
             .toBe('MAT-DIALOG-CONTAINER', 'Expected dialog container to be focused.');
       }));
 
+    it('should be able to disable focus restoration', fakeAsync(() => {
+      // Create a element that has focus before the dialog is opened.
+      const button = document.createElement('button');
+      button.id = 'dialog-trigger';
+      document.body.appendChild(button);
+      button.focus();
+
+      const dialogRef = dialog.open(PizzaMsg, {
+        viewContainerRef: testViewContainerRef,
+        restoreFocus: false
+      });
+
+      flushMicrotasks();
+      viewContainerFixture.detectChanges();
+      flushMicrotasks();
+
+      expect(document.activeElement.id)
+          .not.toBe('dialog-trigger', 'Expected the focus to change when dialog was opened.');
+
+      dialogRef.close();
+      flushMicrotasks();
+      viewContainerFixture.detectChanges();
+      tick(500);
+
+      expect(document.activeElement.id).not.toBe('dialog-trigger',
+          'Expected focus not to have been restored.');
+
+      document.body.removeChild(button);
+    }));
+
+
   });
 
   describe('dialog content elements', () => {