@lifaon/rx-js-light/src/observable/built-in/from/without-notifications/dom/from-resize-observer/from-resize-observer.mjs

Blazing fast Observables

import {createMulticastSource} from "../../../../../../observer-observable-pair/build-in/source/built-in/multicast-source/create-multicast-source.mjs";
import {freeze} from "../../../../../../misc/helpers/freeze.mjs";
let RESIZE_OBSERVER_AND_SUBSCRIPTION_CACHED;
function getResizeObserverAndSubscription() {
  if (RESIZE_OBSERVER_AND_SUBSCRIPTION_CACHED === void 0) {
    const source = createMulticastSource();
    const observer = new ResizeObserver(entries => {
      source.emit(entries);
    });
    RESIZE_OBSERVER_AND_SUBSCRIPTION_CACHED = freeze({
      subscribe: source.subscribe,
      observer
    });
  }
  return RESIZE_OBSERVER_AND_SUBSCRIPTION_CACHED;
}
export function fromResizeObserver(element, options) {
  return emit => {
    let running = true;
    const {subscribe, observer} = getResizeObserverAndSubscription();
    const unsubscribe = subscribe(entries => {
      for (let i = 0, l = entries.length; i < l; i++) {
        const entry = entries[i];
        if (running && entry.target === element) {
          emit(entry);
          break;
        }
      }
    });
    observer.observe(element, options);
    return () => {
      if (running) {
        running = false;
        unsubscribe();
        observer.unobserve(element);
      }
    };
  };
}