Simple cache implementation.

Cache.js

'use strict';

const List = require('./List');

class Cache {
  constructor(capacity = 10) {
    this.capacity = capacity;
    this.size = 0;
    this.list = new List();
    this.dict = {};
  }
  find(key) {
    const node = this.dict[key];
    if (typeof node == 'object') {
      return node.value.value;
    }
  }
  remove(key) {
    const node = this.dict[key];
    if (typeof node == 'object') {
      delete this.dict[key];
      node.pop();
      --this.size;
    }
    return this;
  }
  register(key, value) {
    const node = this.dict[key];
    if (typeof node == 'object') {
      this.list.moveToFront(node);
      node.value = value;
    } else {
      if (this.size >= this.capacity) {
        const node = this.list.back;
        this.list.moveToFront(node);
        delete this.dict[node.value.key];
        this.dict[key] = node;
        node.value = {key, value};
      } else {
        this.list.pushFront({key, value});
        ++this.size;
        this.dict[key] = this.list.front;
      }
    }
    return this;
  }
  clear() {
    this.dict = {};
    this.list.clear();
    this.size = 0;
    return this;
  }
  [Symbol.iterator]() {
    return this.list[Symbol.iterator]();
  }
  getReverseIterable() {
    return this.list.getReverseIterable();
  }
}

module.exports = Cache;

It uses List from https://gist.github.com/uhop/f17409a95a14f10e1cbd5a584ca9d245