// cache.js - Client-side caching utilities
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/**
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* Simple cache implementation with time-based expiration
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*/
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class Cache {
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constructor(options = {}) {
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this.storage = {};
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this.options = {
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defaultTTL: 3600000, // 1 hour in milliseconds
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namespace: 'jvb_cache_',
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useLocalStorage: true,
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...options
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};
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// Load persisted data from localStorage if enabled
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if (this.options.useLocalStorage) {
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this.loadFromStorage();
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}
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}
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/**
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* Set a cache item
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* @param {string} key - Cache key
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* @param {*} value - Value to store
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* @param {number} ttl - Time to live in milliseconds (optional)
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*/
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set(key, value, ttl = this.options.defaultTTL) {
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const cacheKey = this.formatKey(key);
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const expiry = Date.now() + ttl;
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this.storage[cacheKey] = {
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value,
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expiry
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};
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// Persist to localStorage if enabled
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if (this.options.useLocalStorage) {
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this.saveToStorage();
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}
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return value;
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}
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/**
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* Get a cache item
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* @param {string} key - Cache key
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* @param {*} defaultValue - Default value if item not found or expired
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* @returns {*} Cached value or default
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*/
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get(key, defaultValue = null) {
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const cacheKey = this.formatKey(key);
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const item = this.storage[cacheKey];
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// Return default if item doesn't exist
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if (!item) {
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return defaultValue;
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}
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// Check if item has expired
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if (item.expiry < Date.now()) {
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this.remove(key);
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return defaultValue;
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}
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return item.value;
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}
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/**
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* Get or set a cache item
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* @param {string} key - Cache key
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* @param {Function} callback - Function to generate value if not cached
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* @param {number} ttl - Time to live in milliseconds (optional)
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* @returns {*} Cached or generated value
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*/
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getOrSet(key, callback, ttl = this.options.defaultTTL) {
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const value = this.get(key);
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if (value !== null) {
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return value;
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}
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// Generate new value
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const newValue = callback();
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// Store in cache
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return this.set(key, newValue, ttl);
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}
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/**
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* Remove a cache item
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* @param {string} key - Cache key
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*/
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remove(key) {
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const cacheKey = this.formatKey(key);
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delete this.storage[cacheKey];
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// Update localStorage if enabled
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if (this.options.useLocalStorage) {
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this.saveToStorage();
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}
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}
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/**
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* Clear all cache items
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*/
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clear() {
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this.storage = {};
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// Clear from localStorage if enabled
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if (this.options.useLocalStorage) {
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this.clearFromStorage();
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}
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}
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/**
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* Check if a cache item exists and is not expired
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* @param {string} key - Cache key
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* @returns {boolean} True if item exists and is valid
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*/
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has(key) {
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const cacheKey = this.formatKey(key);
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const item = this.storage[cacheKey];
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if (!item) {
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return false;
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}
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return item.expiry >= Date.now();
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}
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/**
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* Format a key with namespace
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* @param {string} key - Original key
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* @returns {string} Namespaced key
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*/
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formatKey(key) {
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return `${this.options.namespace}${key}`;
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}
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/**
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* Save cache to localStorage
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*/
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saveToStorage() {
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try {
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localStorage.setItem('jvb_cache', JSON.stringify({
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timestamp: Date.now(),
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data: this.storage
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}));
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} catch (e) {
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console.warn('Failed to save cache to localStorage:', e);
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}
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}
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/**
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* Load cache from localStorage
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*/
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loadFromStorage() {
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try {
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const stored = localStorage.getItem('jvb_cache');
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if (stored) {
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const parsed = JSON.parse(stored);
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// Only use if not too old (24 hours max)
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const maxAge = 24 * 60 * 60 * 1000; // 24 hours
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if (parsed.timestamp && (Date.now() - parsed.timestamp) < maxAge) {
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this.storage = parsed.data || {};
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// Clean expired items
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this.cleanExpired();
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}
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}
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} catch (e) {
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console.warn('Failed to load cache from localStorage:', e);
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this.storage = {};
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}
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}
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/**
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* Clear cache from localStorage
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*/
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clearFromStorage() {
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try {
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localStorage.removeItem('jvb_cache');
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} catch (e) {
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console.warn('Failed to clear cache from localStorage:', e);
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}
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}
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/**
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* Remove expired items
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*/
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cleanExpired() {
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const now = Date.now();
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Object.keys(this.storage).forEach(key => {
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const item = this.storage[key];
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if (item.expiry < now) {
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delete this.storage[key];
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}
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});
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}
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}
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// Create and export a singleton instance
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const cache = new Cache();
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export default cache;
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// Also export the class for custom instances
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export { Cache };
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