A proof-of-concept for an object-based cache with expiration control.

mini-cache.js

class Cache {
  constructor() {
    this._data = {};
  }
  
  read(key) {
    const now = new Date().valueOf();
    const { expiresAt, value } = this._data[key];
    
    if (now >= expiresAt) {
      this.delete(key);
      return;
    }
    
    return this._data[key];
  }
  
  write(key, value, expires = 3600) {
    const createdAt = new Date().valueOf();
    const expiresAt = createdAt + expires * 1000;
    this._data[key] = { createdAt, expiresAt, value };
    setTimeout(() => this.delete(key), expires * 1000);
  }
  
  delete(key) {
    delete this._data[key];
  }
}

Note to all: this isn't production-ready, it's just something I wrote quickly.