boundedLruCacheWithMapRecency

// Fixed-capacity LRU cache; Map insertion order is the recency order.
export class LruCache {
  #maxSize;
  #items = new Map();

  constructor(maxSize) {
    if (!Number.isInteger(maxSize) || maxSize < 1) {
      throw new RangeError('maxSize must be a positive integer');
    }
    this.#maxSize = maxSize;
  }

  get(key) {
    if (!this.#items.has(key)) return undefined;
    const value = this.#items.get(key);
    this.#items.delete(key);
    this.#items.set(key, value); // move the hit to the most-recent position
    return value;
  }

  set(key, value) {
    this.#items.delete(key);
    this.#items.set(key, value);
    if (this.#items.size > this.#maxSize) {
      this.#items.delete(this.#items.keys().next().value);
    }
    return this;
  }

  get size() {
    return this.#items.size;
  }
}