中文
devexamples

LRU Cache With Map Ordering

Implement a least-recently-used cache that evicts the oldest entry when capacity is exceeded, reusing Map insertion order to track recency.

JavascriptData Fetching

Code

snippet
export class LruCache {
  constructor(capacity) {
    if (capacity <= 0) throw new RangeError("capacity must be positive");
    this.capacity = capacity;
    this.entries = new Map();
  }

  get(key) {
    if (!this.entries.has(key)) return undefined;
    const value = this.entries.get(key);
    this.entries.delete(key);
    this.entries.set(key, value);
    return value;
  }

  set(key, value) {
    if (this.entries.has(key)) this.entries.delete(key);
    this.entries.set(key, value);
    if (this.entries.size > this.capacity) {
      const oldest = this.entries.keys().next().value;
      this.entries.delete(oldest);
    }
  }
}

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