RunKit + npm:

const LFU = require('node-lfu-cache'); const cache = new LFU(50); const random = (min, max) => Math.round(Math.random() * (max - min)) + min; const cacheFunc = (key, value) => { if (cache.has(key)) return cache.get(key); cache.set(key, value); return value; } // Will be called only once cacheFunc('cold', '123'); // Will be called for 10 times for (let i = 1; i <= 10; i++) { cacheFunc('hot', '456'); } // Let the cache size limit exceeded for (let i = 1; i <= 60; i++) { cacheFunc(String(100 + i), random(100, 900)); } console.log('Cold: ' + cacheFunc('cold', '789')); // Should be 789 not 123, because the cold cache will be removed from the cache. console.log('Hot: ' + cacheFunc('hot', '789')); // Should be 456 not 789, because it is hot and remains in the cache.