@zohodesk/components/es/Popup/intersectionObserver.js

In this Package, we Provide Some Basic Components to Build Web App

let observerCallbacks = null;
let intersectionObserver = null;

function handleObserverCallbacks(entries) {
  entries.forEach(entry => {
    let oldCallbacks = observerCallbacks.get(entry.target);

    if (Array.isArray(oldCallbacks) && oldCallbacks.length) {
      oldCallbacks.forEach(callback => {
        callback && callback(entry);
      });
    }
  });
}

export function addIntersectionObserver(element, callback, options) {
  if (!!element && typeof callback == 'function') {
    if (intersectionObserver === null && observerCallbacks === null) {
      intersectionObserver = new IntersectionObserver(entries => {
        handleObserverCallbacks(entries);
      }, options);
      observerCallbacks = new Map();
    }

    intersectionObserver.observe(element);
    let oldCallbacks = observerCallbacks.get(element) || [];
    observerCallbacks.set(element, [...oldCallbacks, callback]);
  }
}
export function removeIntersectionObserver(element, callback) {
  if (!!element && typeof callback == 'function') {
    let oldCallbacks = observerCallbacks ? observerCallbacks.get(element) : null;

    if (Array.isArray(oldCallbacks)) {
      let callbacks = oldCallbacks.filter(handler => handler !== callback);

      if (intersectionObserver && callbacks.length === 0) {
        observerCallbacks.delete(element);
        intersectionObserver.unobserve(element);
      }
    }

    if (intersectionObserver && observerCallbacks && observerCallbacks.size === 0) {
      intersectionObserver.disconnect();
      intersectionObserver = null;
      observerCallbacks = null;
    }
  }
}