localStorage.js

const storageHandler = {
  get(obj, name) {
    return obj.getItem(name) || obj[name];
  },
  set(obj, name, value) {
    obj.setItem(name, value);
  },
  has(obj, name) {
    return name in obj.d || name in obj;
  },
  deleteProperty(obj, name) {
    obj.removeItem(name);
  },
};

class StorageClass {
  constructor() {
    this.d = {};
    this.k = [];
  }
  get length() {
    return this.k.length;
  }
  getItem(name) {
    return this.d[name];
  }
  setItem(name, value) {
    if (!this.k.indexOf(name)) {
      this.k.push(name);
    }
    this.d[name] = value;
  }
  removeItem(name) {
    this.k.pop(this.k.indexOf(name));
    delete this.d[name];
  }
  clear() {
    this.d = {};
    this.k = [];
  }
}

window.localStorage = new Proxy(new StorageClass(), storageHandler);
window.sessionStorage = new Proxy(new StorageClass(), storageHandler);