# 使用 js 实现一个 lru cache
Issue
欢迎在 Gtihub Issue 中回答此问题: Issue 251 (opens new window)
Author
可以借助Map实现
class LRUCache {
constructor(limit) {
this.limit = limit;
this.cache = new Map();
}
get(key) {
if (!this.cache.has(key)) return undefined;
const value = this.cache.get(key);
this.cache.delete(key);
this.cache.set(key, value);
return value;
}
put(key, value) {
if (this.cache.has(key)) this.cache.delete(key);
else if (this.cache.size >= this.limit) {
this.cache.delete(this.cache.keys().next().value);
}
this.cache.set(key, value);
}
}
// ["LRUCache","put","put","get","put","get","put","get","get","get"]
// [[2],[1,1],[2,2],[1],[3,3],[2],[4,4],[1],[3],[4]]
const lruCache = new LRUCache(2);
lruCache.put(1, 1);
lruCache.put(2, 2);
const res1 = lruCache.get(1);
lruCache.put(3, 3);
const res2 = lruCache.get(2);
lruCache.put(4, 4);
const res3 = lruCache.get(1);
const res4 = lruCache.get(3);
const res5 = lruCache.get(4);
console.log(res1, res2, res3, res4, res5);
// 1 undefined undefined 3 4
Author
LRU (最近最少使用) 缓存机制
- 使用 Map 做数据保存
- 自建双向链表做元素使用频率保存及空间大小控制