JavaScript

WeakRef Object Cache

by @admin

12h ago

Apr 28, 2026

Public

A cache backed by WeakRef and FinalizationRegistry. Stored values are held weakly — the garbage collector can reclaim them if memory pressure is high, and the registry automatically cleans up stale entries from the internal map. Ideal for caching large objects (DOM nodes, rendered images) without causing memory leaks.

JavaScript

function createWeakCache() {
  const cache   = new Map();
  const registry = new FinalizationRegistry((key) => cache.delete(key));

  return {
    set(key, value) {
      cache.set(key, new WeakRef(value));
      registry.register(value, key);
    },
    get(key) {
      return cache.get(key)?.deref() ?? null;
    },
    has(key) {
      return this.get(key) !== null;
    },
  };
}

// Usage
const imgCache = createWeakCache();
const img = new Image();
img.src = '/hero.jpg';
imgCache.set('hero', img);
console.log(imgCache.get('hero')); // Image element (while alive)

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