dees-domtools/ts/domtools.classes.scroller.ts

import type { DomTools } from './domtools.classes.domtools.js';
import * as plugins from './domtools.plugins.js';

export class Scroller {
  public domtoolsInstance: DomTools;

  constructor(
    domtoolsInstanceArg: DomTools,
  ) {
    this.domtoolsInstance = domtoolsInstanceArg;
  }

  private sweetScroller = new plugins.SweetScroll({
    /* some options */
  }); // TODO: switch to scroller class

  public async scrollToElement(
    elementArg: HTMLElement,
    optionsArg: Parameters<typeof this.sweetScroller.toElement>[1]
  ) {
    this.sweetScroller.toElement(elementArg, optionsArg);
    await plugins.smartdelay.delayFor(optionsArg.duration);
  }

  public async detectNativeSmoothScroll() {
    const done = plugins.smartpromise.defer<boolean>();
    const sampleSize = 100;
    const acceptableDeltaDifference = 3;
    const minimumSmoothRatio = 0.75;

    const eventDeltas: number[] = [];

    function onWheel(event: WheelEvent) {
      eventDeltas.push(event.deltaY);

      if (eventDeltas.length >= sampleSize) {
        window.removeEventListener('wheel', onWheel);
        analyzeEvents();
      }
    }

    function analyzeEvents() {
      const totalDiffs = eventDeltas.length - 1;
      let smallDiffCount = 0;

      for (let i = 0; i < totalDiffs; i++) {
        const diff = Math.abs(eventDeltas[i + 1] - eventDeltas[i]);
        if (diff <= acceptableDeltaDifference) {
          smallDiffCount++;
        }
      }

      const smoothRatio = smallDiffCount / totalDiffs;
      if (smoothRatio >= minimumSmoothRatio) {
        console.log('Smooth scrolling detected.');
        done.resolve(true);
      } else {
        console.log('Smooth scrolling NOT detected.');
        done.resolve(false);
      }
    }

    window.addEventListener('wheel', onWheel);
    return done.promise;
  }

  public async enableLenisScroll(optionsArg?: { disableOnNativeSmoothScroll?: boolean }) {
    const lenis = new plugins.Lenis({
      autoRaf: true,
    });
    if (optionsArg?.disableOnNativeSmoothScroll) {
      if (await this.detectNativeSmoothScroll()) {
        lenis.destroy();
      }
    }
  }
}