How to get on scroll events?

javascript

event-listeners

scroll-events

angular

byAnton Shumikhin·Oct 24, 2024

Easily detect scroll events using addEventListener on the window or any scrollable element. Here's a basic code snippet for you:

window.addEventListener('scroll', () => console.log('Scrolled!'));

By addEventListener, you're registering a callback function that triggers each time a scrolling action occurs. If you want this function to monitor scrolls on a specific element, simply replace window with your target element's variable.

For those Angular geeks, harness @HostListener to listen for scroll events:

@HostListener('window:scroll', ['$event'])
onWindowScroll(event) {
    // Cue 'Eye of the Tiger' theme...
}

And to catch scroll maneuvers from particular elements, use the (scroll) event binding:

<div (scroll)="onScroll($event)">...</div>

This can be handled in your Angular component like so:

onScroll(event) {
    // Eat, Sleep, Scroll, Repeat!
}

Comprehensive guide to capture Scroll Events

Scroll events are a staple in web development and help developers shed light on user interaction. Let's dive into their effective use:

Angular's Scroll Catcher: @HostListener

@HostListener('window:scroll', ['$event'])
onWindowScroll(e) {
    const scrollPosition = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0;
    console.log(`Scroll Event Detected! Position: ${scrollPosition}`);
    // Added bonus: A bit of fitness while you sit and code!
}

At home with the DOM: @ViewChild and ElementRef

@ViewChild('scrollableElement', {static: true}) scrollableRef: ElementRef;

ngAfterViewInit() {
    this.scrollableRef.nativeElement.addEventListener('scroll', this.onScroll.bind(this));
    // DOM and chill with Angular
}

The RxJS Saga: Reactive Scrolls

fromEvent(window, 'scroll')
  .pipe(
    map(() => window.pageYOffset),
    distinctUntilChanged(),
    filter(position => position > 100)
  )
  .subscribe(() => console.log('I see scroll events over the horizon!'));

This RxJS method offers finer control and efficiency, especially for complex apps.

Stepping up the game: Enhanced Scroll Detection

Binding event listeners, processing scroll positions for various functionalities (like infinite scrolling or dynamic UI updates), and implementing clean-up methods to prevent memory leaks are steps of an enhanced journey in capturing scroll events.

Steer clear of the Icebergs: Tips and potential pitfalls

Navigating through scroll events might bring certain challenges. For instance, high-frequency events can lead to performance issues. Techniques like debouncing or throttling can save your apps from sinking. Additionally, consider using the Intersection Observer API for visibility-related tasks and apply the RxJS operators like throttleTime, auditTime, or sampleTime to manage the tumultuous nature of scroll events.

Don't forget the Captain's tools

Your toolbox can contain instruments like window.pageYOffset for position tracking, @ViewChild to locate elements, and RxJS fromEvent to chart an efficient synchronous path.

explain-codes / Javascript / How to get on scroll events?

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