Enable strict property initialization in the CDK

goldens/cdk/menu/index.api.md

@@ -235,7 +235,7 @@ export abstract class CdkMenuTriggerBase implements OnDestroy {
     abstract close(): void;
     readonly closed: EventEmitter<void>;
     protected readonly destroyed: Subject<void>;
-    protected getMenuContentPortal(): TemplatePortal<any>;
+    protected getMenuContentPortal(): TemplatePortal<any> | undefined;
     readonly injector: Injector;
     protected isElementInsideMenuStack(element: Element): boolean;
     isOpen(): boolean;

goldens/cdk/overlay/index.api.md

@@ -419,7 +419,7 @@ export interface OverlayConnectionPosition {
 export class OverlayContainer implements OnDestroy {
     constructor(...args: unknown[]);
     // (undocumented)
-    protected _containerElement: HTMLElement;
+    protected _containerElement: HTMLElement | undefined;
     protected _createContainer(): void;
     // (undocumented)
     protected _document: Document;

src/cdk/a11y/focus-monitor/focus-monitor.ts

@@ -93,16 +93,16 @@ export class FocusMonitor implements OnDestroy {
   private _origin: FocusOrigin = null;
 
   /** The FocusOrigin of the last focus event tracked by the FocusMonitor. */
-  private _lastFocusOrigin: FocusOrigin;
+  private _lastFocusOrigin: FocusOrigin = null;
 
   /** Whether the window has just been focused. */
   private _windowFocused = false;
 
   /** The timeout id of the window focus timeout. */
-  private _windowFocusTimeoutId: ReturnType<typeof setTimeout>;
+  private _windowFocusTimeoutId: ReturnType<typeof setTimeout> | undefined;
 
   /** The timeout id of the origin clearing timeout. */
-  private _originTimeoutId: ReturnType<typeof setTimeout>;
+  private _originTimeoutId: ReturnType<typeof setTimeout> | undefined;
 
   /**
    * Whether the origin was determined via a touch interaction. Necessary as properly attributing
@@ -617,7 +617,7 @@ export class CdkMonitorFocus implements AfterViewInit, OnDestroy {
   private _elementRef = inject<ElementRef<HTMLElement>>(ElementRef);
   private _focusMonitor = inject(FocusMonitor);
 
-  private _monitorSubscription: Subscription;
+  private _monitorSubscription: Subscription | undefined;
   private _focusOrigin: FocusOrigin = null;
 
   @Output() readonly cdkFocusChange = new EventEmitter<FocusOrigin>();
@@ -641,9 +641,6 @@ export class CdkMonitorFocus implements AfterViewInit, OnDestroy {
 
   ngOnDestroy() {
     this._focusMonitor.stopMonitoring(this._elementRef);
-
-    if (this._monitorSubscription) {
-      this._monitorSubscription.unsubscribe();
-    }
+    this._monitorSubscription?.unsubscribe();
   }
 }

src/cdk/a11y/focus-trap/focus-trap.ts

@@ -36,8 +36,8 @@ import {_CdkPrivateStyleLoader, _VisuallyHiddenLoader} from '../../private';
  * Things like `tabIndex > 0`, flex `order`, and shadow roots can cause the two to be misaligned.
  */
 export class FocusTrap {
-  private _startAnchor: HTMLElement | null;
-  private _endAnchor: HTMLElement | null;
+  private _startAnchor: HTMLElement | null = null;
+  private _endAnchor: HTMLElement | null = null;
   private _hasAttached = false;
 
   // Event listeners for the anchors. Need to be regular functions so that we can unbind them later.
@@ -413,7 +413,7 @@ export class CdkTrapFocus implements OnDestroy, AfterContentInit, OnChanges, DoC
   private _focusTrapFactory = inject(FocusTrapFactory);
 
   /** Underlying FocusTrap instance. */
-  focusTrap: FocusTrap;
+  focusTrap: FocusTrap = undefined!;
 
   /** Previously focused element to restore focus to upon destroy when using autoCapture. */
   private _previouslyFocusedElement: HTMLElement | null = null;
@@ -433,7 +433,8 @@ export class CdkTrapFocus implements OnDestroy, AfterContentInit, OnChanges, DoC
    * Whether the directive should automatically move focus into the trapped region upon
    * initialization and return focus to the previous activeElement upon destruction.
    */
-  @Input({alias: 'cdkTrapFocusAutoCapture', transform: booleanAttribute}) autoCapture: boolean;
+  @Input({alias: 'cdkTrapFocusAutoCapture', transform: booleanAttribute})
+  autoCapture: boolean = false;
 
   constructor(...args: unknown[]);
 

src/cdk/a11y/high-contrast-mode/high-contrast-mode-detector.ts

@@ -47,7 +47,7 @@ export class HighContrastModeDetector implements OnDestroy {
    * Figuring out the high contrast mode and adding the body classes can cause
    * some expensive layouts. This flag is used to ensure that we only do it once.
    */
-  private _hasCheckedHighContrastMode: boolean;
+  private _hasCheckedHighContrastMode = false;
   private _document = inject(DOCUMENT);
   private _breakpointSubscription: Subscription;
 

src/cdk/a11y/key-manager/list-key-manager.ts

@@ -45,7 +45,7 @@ export class ListKeyManager<T extends ListKeyManagerOption> {
   private _typeaheadSubscription = Subscription.EMPTY;
   private _itemChangesSubscription?: Subscription;
   private _vertical = true;
-  private _horizontal: 'ltr' | 'rtl' | null;
+  private _horizontal: 'ltr' | 'rtl' | null = null;
   private _allowedModifierKeys: ListKeyManagerModifierKey[] = [];
   private _homeAndEnd = false;
   private _pageUpAndDown = {enabled: false, delta: 10};

src/cdk/a11y/live-announcer/live-announcer.ts

@@ -43,7 +43,7 @@ export class LiveAnnouncer implements OnDestroy {
   private _liveElement: HTMLElement;
   private _document = inject(DOCUMENT);
   private _sanitizer = inject(DomSanitizer);
-  private _previousTimeout: ReturnType<typeof setTimeout>;
+  private _previousTimeout: ReturnType<typeof setTimeout> | undefined;
   private _currentPromise: Promise<void> | undefined;
   private _currentResolve: (() => void) | undefined;
 
@@ -250,7 +250,7 @@ export class CdkAriaLive implements OnDestroy {
     if (this._politeness === 'off') {
       if (this._subscription) {
         this._subscription.unsubscribe();
-        this._subscription = null;
+        this._subscription = undefined;
       }
     } else if (!this._subscription) {
       this._subscription = this._ngZone.runOutsideAngular(() => {
@@ -271,10 +271,10 @@ export class CdkAriaLive implements OnDestroy {
   private _politeness: AriaLivePoliteness = 'polite';
 
   /** Time in milliseconds after which to clear out the announcer element. */
-  @Input('cdkAriaLiveDuration') duration: number;
+  @Input('cdkAriaLiveDuration') duration!: number;
 
   private _previousAnnouncedText?: string;
-  private _subscription: Subscription | null;
+  private _subscription: Subscription | undefined;
 
   constructor(...args: unknown[]);
 
@@ -283,8 +283,6 @@ export class CdkAriaLive implements OnDestroy {
   }
 
   ngOnDestroy() {
-    if (this._subscription) {
-      this._subscription.unsubscribe();
-    }
+    this._subscription?.unsubscribe();
   }
 }

src/cdk/bidi/dir.ts

@@ -35,7 +35,7 @@ export class Dir implements Directionality, AfterContentInit, OnDestroy {
   private _isInitialized: boolean = false;
 
   /** Direction as passed in by the consumer. */
-  _rawDir: string;
+  _rawDir: string = '';
 
   /** Event emitted when the direction changes. */
   @Output('dirChange') readonly change = new EventEmitter<Direction>();

src/cdk/bidi/directionality.spec.ts

@@ -170,7 +170,7 @@ class InjectsDirectionality {
   imports: [Dir, InjectsDirectionality],
 })
 class ElementWithDir {
-  @ViewChild(Dir) dir: Dir;
+  @ViewChild(Dir) dir!: Dir;
   direction = signal<Direction>('rtl');
   changeCount = 0;
 }
@@ -180,15 +180,15 @@ class ElementWithDir {
   imports: [Dir],
 })
 class ElementWithPredefinedAutoDir {
-  @ViewChild(Dir) dir: Dir;
+  @ViewChild(Dir) dir!: Dir;
 }
 
 @Component({
   template: '<div [dir]="$any(`RTL`)"></div>',
   imports: [Dir],
 })
 class ElementWithPredefinedUppercaseDir {
-  @ViewChild(Dir) dir: Dir;
+  @ViewChild(Dir) dir!: Dir;
 }
 
 interface FakeDocument {

src/cdk/clipboard/copy-to-clipboard.ts

@@ -63,7 +63,7 @@ export class CdkCopyToClipboard implements OnDestroy {
   private _pending = new Set<PendingCopy>();
 
   /** Whether the directive has been destroyed. */
-  private _destroyed: boolean;
+  private _destroyed = false;
 
   /** Timeout for the current copy attempt. */
   private _currentTimeout: any;

src/cdk/collections/selection-model.ts

@@ -22,7 +22,7 @@ export class SelectionModel<T> {
   private _selectedToEmit: T[] = [];
 
   /** Cache for the array value of the selected items. */
-  private _selected: T[] | null;
+  private _selected: T[] | null = null;
 
   /** Selected values. */
   get selected(): T[] {

src/cdk/dialog/dialog-container.ts

@@ -87,7 +87,7 @@ export class CdkDialogContainer<C extends DialogConfig = DialogConfig>
   protected _document = inject(DOCUMENT);
 
   /** The portal outlet inside of this container into which the dialog content will be loaded. */
-  @ViewChild(CdkPortalOutlet, {static: true}) _portalOutlet: CdkPortalOutlet;
+  @ViewChild(CdkPortalOutlet, {static: true}) _portalOutlet!: CdkPortalOutlet;
 
   _focusTrapped: Observable<void> = new Subject<void>();
 

src/cdk/dialog/dialog-ref.ts

@@ -27,16 +27,16 @@ export class DialogRef<R = unknown, C = unknown> {
    * Instance of component opened into the dialog. Will be
    * null when the dialog is opened using a `TemplateRef`.
    */
-  readonly componentInstance: C | null;
+  readonly componentInstance: C | null = null;
 
   /**
    * `ComponentRef` of the component opened into the dialog. Will be
    * null when the dialog is opened using a `TemplateRef`.
    */
-  readonly componentRef: ComponentRef<C> | null;
+  readonly componentRef: ComponentRef<C> | null = null;
 
   /** Instance of the container that is rendering out the dialog content. */
-  readonly containerInstance: DialogContainer;
+  readonly containerInstance!: DialogContainer;
 
   /** Whether the user is allowed to close the dialog. */
   disableClose: boolean | undefined;

src/cdk/drag-drop/directives/drag-placeholder.ts

@@ -30,7 +30,7 @@ export class CdkDragPlaceholder<T = any> implements OnDestroy {
   private _drag = inject(CDK_DRAG_PARENT, {optional: true});
 
   /** Context data to be added to the placeholder template instance. */
-  @Input() data: T;
+  @Input() data!: T;
 
   constructor(...args: unknown[]);
 

src/cdk/drag-drop/directives/drag-preview.ts

@@ -38,7 +38,7 @@ export class CdkDragPreview<T = any> implements OnDestroy {
   private _drag = inject(CDK_DRAG_PARENT, {optional: true});
 
   /** Context data to be added to the preview template instance. */
-  @Input() data: T;
+  @Input() data!: T;
 
   /** Whether the preview should preserve the same size as the item that is being dragged. */
   @Input({transform: booleanAttribute}) matchSize: boolean = false;

src/cdk/drag-drop/directives/drag.ts

@@ -81,14 +81,14 @@ export class CdkDrag<T = any> implements AfterViewInit, OnChanges, OnDestroy {
 
   private readonly _destroyed = new Subject<void>();
   private _handles = new BehaviorSubject<CdkDragHandle[]>([]);
-  private _previewTemplate: CdkDragPreview | null;
-  private _placeholderTemplate: CdkDragPlaceholder | null;
+  private _previewTemplate: CdkDragPreview | null = null;
+  private _placeholderTemplate: CdkDragPlaceholder | null = null;
 
   /** Reference to the underlying drag instance. */
   _dragRef: DragRef<CdkDrag<T>>;
 
   /** Arbitrary data to attach to this drag instance. */
-  @Input('cdkDragData') data: T;
+  @Input('cdkDragData') data!: T;
 
   /** Locks the position of the dragged element along the specified axis. */
   @Input('cdkDragLockAxis') lockAxis: DragAxis | null = null;
@@ -98,27 +98,27 @@ export class CdkDrag<T = any> implements AfterViewInit, OnChanges, OnDestroy {
    * the `cdkDrag` element and going up the DOM. Passing an alternate root element is useful
    * when trying to enable dragging on an element that you might not have access to.
    */
-  @Input('cdkDragRootElement') rootElementSelector: string;
+  @Input('cdkDragRootElement') rootElementSelector!: string;
 
   /**
    * Node or selector that will be used to determine the element to which the draggable's
    * position will be constrained. If a string is passed in, it'll be used as a selector that
    * will be matched starting from the element's parent and going up the DOM until a match
    * has been found.
    */
-  @Input('cdkDragBoundary') boundaryElement: string | ElementRef<HTMLElement> | HTMLElement;
+  @Input('cdkDragBoundary') boundaryElement!: string | ElementRef<HTMLElement> | HTMLElement;
 
   /**
    * Amount of milliseconds to wait after the user has put their
    * pointer down before starting to drag the element.
    */
-  @Input('cdkDragStartDelay') dragStartDelay: DragStartDelay;
+  @Input('cdkDragStartDelay') dragStartDelay!: DragStartDelay;
 
   /**
    * Sets the position of a `CdkDrag` that is outside of a drop container.
    * Can be used to restore the element's position for a returning user.
    */
-  @Input('cdkDragFreeDragPosition') freeDragPosition: Point;
+  @Input('cdkDragFreeDragPosition') freeDragPosition!: Point;
 
   /** Whether starting to drag this element is disabled. */
   @Input({alias: 'cdkDragDisabled', transform: booleanAttribute})
@@ -129,7 +129,7 @@ export class CdkDrag<T = any> implements AfterViewInit, OnChanges, OnDestroy {
     this._disabled = value;
     this._dragRef.disabled = this._disabled;
   }
-  private _disabled: boolean;
+  private _disabled = false;
 
   /**
    * Function that can be used to customize the logic of how the position of the drag item
@@ -140,7 +140,7 @@ export class CdkDrag<T = any> implements AfterViewInit, OnChanges, OnDestroy {
   @Input('cdkDragConstrainPosition') constrainPosition?: DragConstrainPosition;
 
   /** Class to be added to the preview element. */
-  @Input('cdkDragPreviewClass') previewClass: string | string[];
+  @Input('cdkDragPreviewClass') previewClass!: string | string[];
 
   /**
    * Configures the place into which the preview of the item will be inserted. Can be configured
@@ -155,7 +155,7 @@ export class CdkDrag<T = any> implements AfterViewInit, OnChanges, OnDestroy {
    * - `ElementRef<HTMLElement> | HTMLElement` - Preview will be inserted into a specific element.
    * Same advantages and disadvantages as `parent`.
    */
-  @Input('cdkDragPreviewContainer') previewContainer: PreviewContainer;
+  @Input('cdkDragPreviewContainer') previewContainer!: PreviewContainer;
 
   /**
    * If the parent of the dragged element has a `scale` transform, it can throw off the