@techmely/utils/useObserverElement.js

Collection of helpful JavaScript / TypeScript utils

'use strict';

/*!
 * @techmely/utils
 * Copyright(c) 2021-2024 Techmely <techmely.creation@gmail.com>
 * MIT Licensed
 */


// src/invariant.ts
var prefix = "Invariant failed";
function invariant(condition, message) {
  if (condition) {
    return;
  }
  if (typeof message === "string" || typeof message === "function") {
    const provided = typeof message === "function" ? message() : message;
    const value = provided ? `${prefix}: ${provided}` : prefix;
    throw new Error(value);
  }
  if (message)
    throw message;
  throw new Error(prefix);
}

// src/isBrowser.ts
function isBrowser() {
  return typeof window !== "undefined";
}

// src/useObserverElement.ts
function useObserverElement() {
  invariant(isBrowser());
  let observer = null;
  const callbacks = /* @__PURE__ */ new Map();
  const observe = (element, callback) => {
    if (!observer) {
      observer = new IntersectionObserver((entries) => {
        for (const entry of entries) {
          const callback2 = callbacks.get(entry.target);
          const isVisible = entry.isIntersecting || entry.intersectionRatio > 0;
          if (isVisible && callback2) {
            callback2();
          }
        }
      });
    }
    callbacks.set(element, callback);
    observer.observe(element);
    return () => {
      callbacks.delete(element);
      observer?.unobserve(element);
      if (callbacks.size === 0) {
        observer?.disconnect();
        observer = null;
      }
    };
  };
  return observe;
}

exports.useObserverElement = useObserverElement;