ember-in-viewport/addon/utils/can-use-intersection-observer.js

Detect if an Ember View or Component is in the viewport @ 60FPS

// Adapted from WC3's intersection polyfill
// https://github.com/w3c/IntersectionObserver/blob/master/polyfill/intersection-observer.js

import canUseDOM from 'ember-in-viewport/utils/can-use-dom';

function checkIntersectionObserver(window) {
  if (
    'IntersectionObserver' in window &&
    'IntersectionObserverEntry' in window &&
    'intersectionRatio' in window.IntersectionObserverEntry.prototype
  ) {
    // Minimal polyfill for Edge 15's lack of `isIntersecting`
    // See: https://github.com/w3c/IntersectionObserver/issues/211
    if (!('isIntersecting' in window.IntersectionObserverEntry.prototype)) {
      Object.defineProperty(
        window.IntersectionObserverEntry.prototype,
        'isIntersecting',
        {
          get: function () {
            return this.intersectionRatio > 0;
          },
        }
      );
    }
    return true;
  }
  return false;
}

export default function canUseIntersectionObserver() {
  if (!canUseDOM) {
    return false;
  }

  return checkIntersectionObserver(window);
}