1  'use strict'
 2  
 3  class LRUCache {
 4    constructor () {
 5      this.max = 1000
 6      this.map = new Map()
 7    }
 8  
 9    get (key) {
10      const value = this.map.get(key)
11      if (value === undefined) {
12        return undefined
13      } else {
14        // Remove the key from the map and add it to the end
15        this.map.delete(key)
16        this.map.set(key, value)
17        return value
18      }
19    }
20  
21    delete (key) {
22      return this.map.delete(key)
23    }
24  
25    set (key, value) {
26      const deleted = this.delete(key)
27  
28      if (!deleted && value !== undefined) {
29        // If cache is full, delete the least recently used item
30        if (this.map.size >= this.max) {
31          const firstKey = this.map.keys().next().value
32          this.delete(firstKey)
33        }
34  
35        this.map.set(key, value)
36      }
37  
38      return this
39    }
40  }
41  
42  module.exports = LRUCache