Answer:49: rxjs hold to save;

apps/rxjs/49-hold-to-save-button/src/app/app.component.ts

@@ -1,25 +1,65 @@
-import { ChangeDetectionStrategy, Component } from '@angular/core';
+import {
+  ChangeDetectionStrategy,
+  Component,
+  ElementRef,
+  viewChild,
+} from '@angular/core';
+import {
+  BTN_SEND_TRIGGER_INTERVAL,
+  PROGRESS_INITIAL_VALUE,
+  PROGRESS_MAX_VALUE,
+  PROGRESS_UPDATE_COUNT,
+} from '../constants/app.constants';
+import { HoldableDirective } from './holdable.directive';
 
 @Component({
-  imports: [],
+  imports: [HoldableDirective],
   selector: 'app-root',
   template: `
     <main class="flex h-screen items-center justify-center">
       <div
         class="flex w-full max-w-screen-sm flex-col items-center gap-y-8 p-4">
         <button
+          holdable
+          [updateInterval]="BTN_SEND_TRIGGER_INTERVAL"
+          (onInterval)="updateProgress()"
+          (onRelease)="resetProgress()"
+          (onComplete)="onSend()"
           class="rounded bg-indigo-600 px-4 py-2 font-bold text-white transition-colors ease-in-out hover:bg-indigo-700">
           Hold me
         </button>
 
-        <progress [value]="20" [max]="100"></progress>
+        <progress
+          #progress
+          [value]="PROGRESS_INITIAL_VALUE"
+          [max]="PROGRESS_MAX_VALUE"></progress>
       </div>
     </main>
   `,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class AppComponent {
-  onSend() {
+  progress = viewChild<string, ElementRef<HTMLProgressElement>>('progress', {
+    read: ElementRef,
+  });
+
+  readonly PROGRESS_INITIAL_VALUE = PROGRESS_INITIAL_VALUE;
+  readonly PROGRESS_MAX_VALUE = PROGRESS_MAX_VALUE;
+  readonly BTN_SEND_TRIGGER_INTERVAL = BTN_SEND_TRIGGER_INTERVAL;
+
+  onSend(): void {
     console.log('Save it!');
   }
+
+  resetProgress(): void {
+    this.progress().nativeElement.value = this.PROGRESS_INITIAL_VALUE;
+  }
+
+  updateProgress(): void {
+    const progressEl = this.progress().nativeElement;
+    const currentVal = progressEl.value;
+    const increment = this.PROGRESS_MAX_VALUE / PROGRESS_UPDATE_COUNT;
+
+    progressEl.value = currentVal + increment;
+  }
 }

apps/rxjs/49-hold-to-save-button/src/app/holdable.directive.ts

@@ -0,0 +1,91 @@
+import {
+  Directive,
+  DOCUMENT,
+  ElementRef,
+  inject,
+  input,
+  OnDestroy,
+  OnInit,
+  output,
+} from '@angular/core';
+import {
+  fromEvent,
+  last,
+  merge,
+  Observable,
+  Subject,
+  switchMap,
+  take,
+  takeUntil,
+  tap,
+  timer,
+} from 'rxjs';
+import { PROGRESS_UPDATE_COUNT } from '../constants/app.constants';
+
+@Directive({
+  selector: '[holdable]',
+})
+export class HoldableDirective implements OnInit, OnDestroy {
+  updateInterval = input.required<number>();
+  numberOfUpdates = input<number>(PROGRESS_UPDATE_COUNT);
+
+  /** emitted on each `updateInterval` */
+  onInterval = output();
+  /** emitted only when `pointerup`, `pointerleave` events are fired. */
+  onRelease = output();
+  /** emitted once the `numberOfUpdates` is reached */
+  onComplete = output();
+
+  private _destroy$ = new Subject<void>();
+  private _document = inject(DOCUMENT);
+  private _el: ElementRef<HTMLButtonElement> = inject(ElementRef);
+
+  ngOnInit(): void {
+    merge(
+      fromEvent(this._el.nativeElement, 'pointerdown'),
+      fromEvent(this._el.nativeElement, 'touchstart'),
+    )
+      .pipe(
+        switchMap(() => {
+          return this._startTimer$();
+        }),
+        takeUntil(this._destroy$),
+      )
+      .subscribe({
+        next: () => {
+          this.onComplete.emit();
+        },
+      });
+  }
+
+  ngOnDestroy(): void {
+    this._destroy$.next();
+    this._destroy$.complete();
+  }
+
+  /**
+   * Updates Progress bar every second
+   *
+   * Emits when the `PROGRESS_UPDATE_COUNT` is reached
+   *
+   * Completes when the `PROGRESS_UPDATE_COUNT` is reached or either of the `mouseup` or `mouseleave` event is fired. If event is fired before reaching the count, no emission occurs and the stream simply completes.
+   */
+  private _startTimer$(): Observable<number> {
+    const mouseleave$ = merge(
+      fromEvent(this._document, 'pointerup'),
+      fromEvent(this._el.nativeElement, 'pointerleave'),
+    ).pipe(tap(() => this.onRelease.emit()));
+
+    return timer(this.updateInterval(), this.updateInterval()).pipe(
+      tap(() => this.onInterval.emit()),
+      take(this.numberOfUpdates()),
+      last(),
+      takeUntil(mouseleave$),
+      // Due to `take` above, the stream is completed and takeUntil is unsubscribed
+      // so `onRelease` needs to be triggered on a different `mouseleave$`
+      tap(() => {
+        mouseleave$.pipe(take(1)).subscribe({});
+      }),
+    );
+  }
+}

apps/rxjs/49-hold-to-save-button/src/constants/app.constants.ts

@@ -0,0 +1,8 @@
+// all intervals, delay, timeouts in milliseconds
+
+export const PROGRESS_INITIAL_VALUE: number = 0;
+export const PROGRESS_MAX_VALUE: number = 100;
+/** number of progress updates to reach completion */
+export const PROGRESS_UPDATE_COUNT: number = 5;
+/** progress update interval */
+export const BTN_SEND_TRIGGER_INTERVAL: number = 300;

apps/rxjs/49-hold-to-save-button/tsconfig.json

@@ -5,13 +5,14 @@
     "esModuleInterop": true,
     "forceConsistentCasingInFileNames": true,
     "strict": true,
+    "strictNullChecks": false,
     "noImplicitOverride": true,
     "noPropertyAccessFromIndexSignature": true,
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
     "module": "preserve",
     "moduleResolution": "bundler",
-    "lib": ["dom", "es2022"]
+    "lib": ["dom", "es2022"],
   },
   "files": [],
   "include": [],