@applicaster/zapp-react-native-utils/appUtils/imageCache/index.js

Applicaster Zapp React Native utilities package

import { Image } from "./Image";

/**
 * Image Cache manager. It is exported as such to behave
 * as a singleton and make sure the cache is shared across
 * all components in the app
 */
export const ImageCache = (function (cache, imageCache) {
  /**
   * adds an image to the cached based on its url
   * if it's already there, will be skipped.
   * the object stored in the cache is an `Image` object
   * constructed from the provided url
   * @param {string} imageUrl to set the cache for.
   */
  imageCache.cache = function (imageUrl) {
    if (cache.has(imageUrl)) {
      return cache.get(imageUrl);
    } else {
      const image = new Image(imageUrl);
      cache.set(imageUrl, image);

      return image;
    }
  };

  /**
   * removes an image from the cache
   */
  imageCache.remove = function (imageUrl) {
    cache.delete(imageUrl);
  };

  /**
   * retrieves an image from the cache. if it doesn't exist, will return null
   * @param {string} imageUrl
   * @returns {Image}
   */
  imageCache.get = function (imageUrl) {
    return cache.has(imageUrl) ? cache.get(imageUrl) : null;
  };

  /**
   * resets the cache by clearing all entries
   * only used for tests ! will do nothing if not in test env.
   */
  imageCache.reset = function () {
    if (process.env.NODE_ENV === "test") {
      cache.clear();
    }
  };

  return imageCache;
})(new Map(), {});