@thejlifex/ngx-scroll-spy
Version:
An Angular library that can spy the position of elements (inside a scrollable container) and emit the currently active (visible) element in the viewport.
84 lines • 12.1 kB
JavaScript
import { Subject, fromEvent, debounceTime } from 'rxjs';
/**
* Encapsulates the logic for scroll spy on a scrollable element (`scrollContainer`).
*
* Scroll spy uses the [Intersection Observer API](https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API).
*
* Supports window resizing.
*
* Inspired by:
* - https://grafikart.fr/tutoriels/scrollspy-js-page-491
* - https://codepen.io/diaphragm/pen/bGNBVxw
* - https://github.com/chefomar/angular-scroll-spy
*/
export class ScrollSpy {
constructor({ scrollContainer } = {}) {
this.spyTargetIsIntersectingSubject$ = new Subject();
/**
* Is emitted when a spy-target has transitioned into a state of intersection (`isIntersecting: true`) or out of a state of intersection (`isIntersecting: false`).
*/
this.spyTargetIsIntersecting$ = this.spyTargetIsIntersectingSubject$.asObservable();
this.spyTargets = [];
this.intersectionObserver = null;
this.resizeDebounceTime = 300;
/**
* Defines the (vertical) position of the IntersectionObserver line.
* Value between `0` (at the top) and `100` (at the bottom).
*
* @todo (For a future version of ngx-scroll-spy) This property should be configured by the user.
*/
this.offset = 20;
this.initIntersectionObserver(scrollContainer);
this.resizeSubscription = fromEvent(window, 'resize').pipe(debounceTime(this.resizeDebounceTime)).subscribe(() => this.initIntersectionObserver(scrollContainer));
}
/**
* Adds a spy-target and starts to observe that target.
*/
addTarget(spyTarget) {
this.spyTargets.push(spyTarget);
this.intersectionObserver?.observe(spyTarget.element);
}
/**
* Removes a spy-target and stops observing that target.
*/
removeTarget(spyTarget) {
this.spyTargets = this.spyTargets.filter(spyTarget => spyTarget.id !== spyTarget.id);
this.intersectionObserver?.unobserve(spyTarget.element);
}
/**
* Stops observing all spy-targets and completes spyTargetIsIntersecting$ subject.
*/
stopSpying() {
this.resizeSubscription?.unsubscribe();
this.intersectionObserver?.disconnect();
this.intersectionObserver = null;
this.spyTargets = [];
this.spyTargetIsIntersectingSubject$.complete();
}
/**
* Initialize IntersectionObserver.
*/
initIntersectionObserver(scrollContainer) {
this.intersectionObserver?.disconnect();
this.intersectionObserver = new IntersectionObserver((entries) => this.intersectionObserverCallback(entries), {
root: scrollContainer,
rootMargin: `-${this.offset}% 0px -${100 - this.offset}% 0px` // IntersectionObserver as one line.
});
for (const spyTarget of this.spyTargets) {
this.intersectionObserver.observe(spyTarget.element);
}
}
/**
* A function which is called when one or more spy-targets have transitioned into a state of intersection (`isIntersecting: true`) or out of a state of intersection (`isIntersecting: false`).
*/
intersectionObserverCallback(entries) {
for (const entry of entries) {
const spyTarget = this.spyTargets.find((item) => item.element === entry.target);
this.spyTargetIsIntersectingSubject$.next({
spyTarget,
isIntersecting: entry.isIntersecting
});
}
}
}
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https://grafikart.fr/tutoriels/scrollspy-js-page-491\r\n * - https://codepen.io/diaphragm/pen/bGNBVxw\r\n * - https://github.com/chefomar/angular-scroll-spy\r\n */\r\nexport class ScrollSpy {\r\n\r\n  private readonly spyTargetIsIntersectingSubject$: Subject<SpyTargetIsIntersectingEvent> = new Subject<SpyTargetIsIntersectingEvent>();\r\n  /**\r\n   * Is emitted when a spy-target has transitioned into a state of intersection (`isIntersecting: true`) or out of a state of intersection (`isIntersecting: false`).\r\n   */\r\n  readonly spyTargetIsIntersecting$: Observable<SpyTargetIsIntersectingEvent> = this.spyTargetIsIntersectingSubject$.asObservable();\r\n  private resizeSubscription?: Subscription;\r\n  private spyTargets: SpyTarget[] = [];\r\n  private intersectionObserver: IntersectionObserver | null = null;\r\n  private readonly resizeDebounceTime: number = 300;\r\n  /**\r\n   * Defines the (vertical) position of the IntersectionObserver line.\r\n   * Value between `0` (at the top) and `100` (at the bottom).\r\n   *\r\n   * @todo (For a future version of ngx-scroll-spy) This property should be configured by the user.\r\n   */\r\n  private readonly offset: number = 20;\r\n\r\n  constructor({ scrollContainer }: ScrollSpyOptions = {}) {\r\n    this.initIntersectionObserver(scrollContainer);\r\n\r\n    this.resizeSubscription = fromEvent(window, 'resize').pipe(\r\n      debounceTime(this.resizeDebounceTime)\r\n    ).subscribe(() => this.initIntersectionObserver(scrollContainer));\r\n  }\r\n\r\n  /**\r\n   * Adds a spy-target and starts to observe that target.\r\n   */\r\n  addTarget(spyTarget: SpyTarget): void {\r\n    this.spyTargets.push(spyTarget);\r\n    this.intersectionObserver?.observe(spyTarget.element);\r\n  }\r\n\r\n  /**\r\n   * Removes a spy-target and stops observing that target.\r\n   */\r\n  removeTarget(spyTarget: SpyTarget): void {\r\n    this.spyTargets = this.spyTargets.filter(spyTarget => spyTarget.id !== spyTarget.id);\r\n    this.intersectionObserver?.unobserve(spyTarget.element);\r\n  }\r\n\r\n  /**\r\n   * Stops observing all spy-targets and completes spyTargetIsIntersecting$ subject.\r\n   */\r\n  stopSpying(): void {\r\n    this.resizeSubscription?.unsubscribe();\r\n    this.intersectionObserver?.disconnect();\r\n    this.intersectionObserver = null;\r\n    this.spyTargets = [];\r\n    this.spyTargetIsIntersectingSubject$.complete();\r\n  }\r\n\r\n  /**\r\n   * Initialize IntersectionObserver.\r\n   */\r\n  private initIntersectionObserver(scrollContainer?: Element): void {\r\n    this.intersectionObserver?.disconnect();\r\n    this.intersectionObserver = new IntersectionObserver(\r\n      (entries) => this.intersectionObserverCallback(entries),\r\n      {\r\n        root: scrollContainer,\r\n        rootMargin: `-${this.offset}% 0px -${100 - this.offset}% 0px` // IntersectionObserver as one line.\r\n      }\r\n    );\r\n    for (const spyTarget of this.spyTargets) {\r\n      this.intersectionObserver.observe(spyTarget.element);\r\n    }\r\n  }\r\n\r\n  /**\r\n   * A function which is called when one or more spy-targets have transitioned into a state of intersection (`isIntersecting: true`) or out of a state of intersection (`isIntersecting: false`).\r\n   */\r\n  private intersectionObserverCallback(entries: IntersectionObserverEntry[]): void {\r\n    for (const entry of entries) {\r\n      const spyTarget = this.spyTargets.find((item) => item.element === entry.target)!;\r\n      this.spyTargetIsIntersectingSubject$.next({\r\n        spyTarget,\r\n        isIntersecting: entry.isIntersecting\r\n      });\r\n    }\r\n  }\r\n}\r\n"]}