refactor(list): remove redundant focus logic (#12965)

Currently both the regular list and the selection list have focus and blur handlers whose job it is to toggle a focused class. This is redundant, because the same can be achieved with a `:focus` selector, without having to go through change detection.

Author: crisbeto

src/lib/list/_list-theme.scss

@@ -28,7 +28,7 @@
 
   .mat-list-option,
   .mat-nav-list .mat-list-item {
-    &:hover, &.mat-list-item-focus {
+    &:hover, &:focus {
       background: mat-color($background, 'hover');
     }
   }

src/lib/list/list.spec.ts

@@ -28,23 +28,6 @@ describe('MatList', () => {
     TestBed.compileComponents();
   }));
 
-  it('should add and remove focus class on focus/blur', () => {
-    let fixture = TestBed.createComponent(ListWithOneAnchorItem);
-    fixture.detectChanges();
-    let listItem = fixture.debugElement.query(By.directive(MatListItem));
-    let listItemEl = fixture.debugElement.query(By.css('.mat-list-item'));
-
-    expect(listItemEl.nativeElement.classList).not.toContain('mat-list-item-focus');
-
-    listItem.componentInstance._handleFocus();
-    fixture.detectChanges();
-    expect(listItemEl.nativeElement.classList).toContain('mat-list-item-focus');
-
-    listItem.componentInstance._handleBlur();
-    fixture.detectChanges();
-    expect(listItemEl.nativeElement.classList).not.toContain('mat-list-item-focus');
-  });
-
   it('should not apply any additional class to a list without lines', () => {
     let fixture = TestBed.createComponent(ListWithOneItem);
     let listItem = fixture.debugElement.query(By.css('mat-list-item'));

src/lib/list/list.ts

@@ -107,8 +107,6 @@ export class MatListSubheaderCssMatStyler {}
     // @breaking-change 7.0.0 Remove `mat-list-item-avatar` in favor of `mat-list-item-with-avatar`.
     '[class.mat-list-item-avatar]': '_avatar || _icon',
     '[class.mat-list-item-with-avatar]': '_avatar || _icon',
-    '(focus)': '_handleFocus()',
-    '(blur)': '_handleBlur()',
   },
   inputs: ['disableRipple'],
   templateUrl: 'list-item.html',
@@ -148,14 +146,6 @@ export class MatListItem extends _MatListItemMixinBase implements AfterContentIn
     return !this._isNavList || this.disableRipple || this._navList.disableRipple;
   }
 
-  _handleFocus() {
-    this._element.nativeElement.classList.add('mat-list-item-focus');
-  }
-
-  _handleBlur() {
-    this._element.nativeElement.classList.remove('mat-list-item-focus');
-  }
-
   /** Retrieves the DOM element of the component host. */
   _getHostElement(): HTMLElement {
     return this._element.nativeElement;

src/lib/list/selection-list.spec.ts

@@ -52,21 +52,6 @@ describe('MatSelectionList without forms', () => {
       selectionList = fixture.debugElement.query(By.directive(MatSelectionList));
     }));
 
-    it('should add and remove focus class on focus/blur', () => {
-      // Use the second list item, because the first one is always disabled.
-      const listItem = listOptions[1].nativeElement;
-
-      expect(listItem.classList).not.toContain('mat-list-item-focus');
-
-      dispatchFakeEvent(listItem, 'focus');
-      fixture.detectChanges();
-      expect(listItem.className).toContain('mat-list-item-focus');
-
-      dispatchFakeEvent(listItem, 'blur');
-      fixture.detectChanges();
-      expect(listItem.className).not.toContain('mat-list-item-focus');
-    });
-
     it('should be able to set a value on a list option', () => {
       const optionValues = ['inbox', 'starred', 'sent-mail', 'drafts'];
 
@@ -519,45 +504,6 @@ describe('MatSelectionList without forms', () => {
     });
   });
 
-  describe('with single option', () => {
-    let fixture: ComponentFixture<SelectionListWithOnlyOneOption>;
-    let listOption: DebugElement;
-    let listItemEl: DebugElement;
-
-    beforeEach(async(() => {
-      TestBed.configureTestingModule({
-        imports: [MatListModule],
-        declarations: [
-          SelectionListWithListOptions,
-          SelectionListWithCheckboxPositionAfter,
-          SelectionListWithListDisabled,
-          SelectionListWithOnlyOneOption
-        ],
-      });
-
-      TestBed.compileComponents();
-    }));
-
-    beforeEach(async(() => {
-      fixture = TestBed.createComponent(SelectionListWithOnlyOneOption);
-      listOption = fixture.debugElement.query(By.directive(MatListOption));
-      listItemEl = fixture.debugElement.query(By.css('.mat-list-item'));
-      fixture.detectChanges();
-    }));
-
-    it('should be focused when focus on nativeElements', () => {
-      dispatchFakeEvent(listOption.nativeElement, 'focus');
-      fixture.detectChanges();
-
-      expect(listItemEl.nativeElement.className).toContain('mat-list-item-focus');
-
-      dispatchFakeEvent(listOption.nativeElement, 'blur');
-      fixture.detectChanges();
-
-      expect(listItemEl.nativeElement.className).not.toContain('mat-list-item-focus');
-    });
-  });
-
   describe('with option disabled', () => {
     let fixture: ComponentFixture<SelectionListWithDisabledOption>;
     let listOptionEl: HTMLElement;

src/lib/list/selection-list.ts

@@ -85,7 +85,6 @@ export class MatSelectionListChange {
     '(click)': '_handleClick()',
     'tabindex': '-1',
     '[class.mat-list-item-disabled]': 'disabled',
-    '[class.mat-list-item-focus]': '_hasFocus',
     '[class.mat-list-item-with-avatar]': '_avatar || _icon',
     '[attr.aria-selected]': 'selected.toString()',
     '[attr.aria-disabled]': 'disabled.toString()',
@@ -100,9 +99,6 @@ export class MatListOption extends _MatListOptionMixinBase
   private _selected = false;
   private _disabled = false;
 
-  /** Whether the option has focus. */
-  _hasFocus: boolean = false;
-
   @ContentChild(MatListAvatarCssMatStyler) _avatar: MatListAvatarCssMatStyler;
   @ContentChild(MatListIconCssMatStyler) _icon: MatListIconCssMatStyler;
   @ContentChildren(MatLine) _lines: QueryList<MatLine>;
@@ -212,12 +208,10 @@ export class MatListOption extends _MatListOptionMixinBase
   }
 
   _handleFocus() {
-    this._hasFocus = true;
     this.selectionList._setFocusedOption(this);
   }
 
   _handleBlur() {
-    this._hasFocus = false;
     this.selectionList._onTouched();
   }
 
@@ -392,9 +386,9 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements Focu
 
   /** Removes an option from the selection list and updates the active item. */
   _removeOptionFromList(option: MatListOption) {
-    if (option._hasFocus) {
-      const optionIndex = this._getOptionIndex(option);
+    const optionIndex = this._getOptionIndex(option);
 
+    if (optionIndex > -1 && this._keyManager.activeItemIndex === optionIndex) {
       // Check whether the option is the last item
       if (optionIndex > 0) {
         this._keyManager.setPreviousItemActive();