service visibility.service.ts

38.09% Statements 8/21

46.15% Branches 6/13

25% Functions 1/4

23.52% Lines 4/17

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  import { ElementRef, Injectable } from '@angular/core';
 
@Injectable({
  providedIn: 'root'
})
export class VisibilityService {
  private observer?: IntersectionObserver;
  private observedElements = new Map<Element, () => void>();
 
  constructor() {
    Iif (('IntersectionObserver' in window)) {
      this.observer = new IntersectionObserver((entries) => {
        entries.forEach((entry) => {
          if (entry.isIntersecting) {
            const cb = this.observedElements.get(entry.target);
            if (cb) {
              cb();
              this.observer!.unobserve(entry.target);
              this.observedElements.delete(entry.target);
            }
          }
        }, {
          rootMargin: '200px'
        });
      });
    }
  }
 
  public notifyVisible(element: ElementRef, callback: () => void) {
    if (!('IntersectionObserver' in window)) {
      // Fallback for unsupported browsers
      callback();
      return;
    }
    this.observer!.observe(element.nativeElement);
    this.observedElements.set(element.nativeElement, callback);
  }
}