react-avatar/es/cache.js

Universal React avatar component makes it possible to generate avatars based on user information.

export const CACHE_PREFIX = 'react-avatar/';
export const CACHE_KEY_FAILING = 'failing';
const _hasLocalStorage = function isLocalStorageAvailable() {
  try {
    return 'localStorage' in window && window['localStorage'];
  } catch (err) {
    return false;
  }
}();
export class Cache {
  constructor() {
    let options = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
    const {
      cachePrefix = CACHE_PREFIX,
      sourceTTL = 7 * 24 * 3600 * 1000,
      sourceSize = 20
    } = options;
    this.cachePrefix = cachePrefix;
    this.sourceTTL = sourceTTL;
    this.sourceSize = sourceSize;
  }
  set(key, value) {
    // cache not available
    if (!_hasLocalStorage) return;
    value = JSON.stringify(value);
    try {
      localStorage.setItem(this.cachePrefix + key, value);
    } catch (e) {
      // failsafe for mobile Safari private mode
      console.error(e); // eslint-disable-line no-console
    }
  }
  get(key) {
    // cache not available
    if (!_hasLocalStorage) return null;
    const value = localStorage.getItem(this.cachePrefix + key);
    if (value) return JSON.parse(value);
    return null;
  }
  sourceFailed(source) {
    let cacheList = this.get(CACHE_KEY_FAILING) || [];

    // Remove expired entries or previous instances of this source
    cacheList = cacheList.filter(entry => {
      const hasExpired = entry.expires > 0 && entry.expires < Date.now();
      const isMatch = entry === source || entry.url == source;
      return !hasExpired && !isMatch;
    });

    // Add the source to the end of the list
    cacheList.unshift({
      url: source,
      expires: Date.now() + this.sourceTTL
    });

    // only keep the last X results so we don't fill up local storage
    cacheList = cacheList.slice(0, this.sourceSize - 1);
    return this.set(CACHE_KEY_FAILING, cacheList);
  }
  hasSourceFailedBefore(source) {
    const cacheList = this.get(CACHE_KEY_FAILING) || [];
    return cacheList.some(entry => {
      const hasExpired = entry.expires > 0 && entry.expires < Date.now();
      const isMatch = entry === source || entry.url == source;
      return isMatch && !hasExpired;
    });
  }
}
export default new Cache();