JAVASCRIPT

Scroll, Position

      
      abstract class ViewportScroller {
  abstract setOffset(offset: [number, number] | (() => [number, number])): void
  abstract getScrollPosition(): [number, number]
  abstract scrollToPosition(position: [number, number]): void
  abstract scrollToAnchor(anchor: string): void
  abstract setHistoryScrollRestoration(scrollRestoration: "auto" | "manual"): void
}
    

Scroll,Position

import { HostListener } from '@angular/core';

@ViewChild('curtain') divCurtain: ElementRef;

export class ComponentX {
    @HostListener('window:scroll', ['$event']) onScrollEvent($event) {
        console.log(window.pageYOffset);
        this.divCurtain.nativeElement.style.top = window.pageYOffset.toString().concat('px');
    }

    ngOnInit(): void { }
}

scroll position

$(window).scroll(function() {
	var $height = $(window).scrollTop();
  if($height > 50) {
		//do something
	} else {
		//do something
	}
});