smooth scroll to in angular

scroll.service.ts

import { Injectable, NgZone } from '@angular/core';

@Injectable()
export class ScrollService {

    constructor(
        private ngZone: NgZone) {
    }

    scrollTo(selector: string, focus?: boolean): void {

        const element = document.querySelector(selector) as HTMLElement;
        if (!element) return;

        const start = element.offsetParent.scrollTop;
        const end = element.offsetTop -
            (element.offsetParent.clientHeight - element.offsetHeight) / 2;
        const stepsTotal = 25;
        let steps = stepsTotal;

        this.ngZone.runOutsideAngular(() => {
            const move = () => {

                requestAnimationFrame(() => {
                    element.offsetParent.scrollTop = start +
                        (end - start) * Math.cos(--steps / stepsTotal * Math.PI / 2);

                    if (steps) setTimeout(move, 10);
                    else if (focus) element.focus();
                });
            };

            move();
        });
    }
}