Basic store

class Storage {
  constructor() {
    this.storage = {};
  }

  list() {
    return Promise.resolve(Object.keys(this.storage))
  }

  fetch(key) {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        const res = this.storage[key];
        res ? resolve(res) : reject('Not found');
      }, 1000)
    })
  }

  store(key, data) {
    this.storage[key] = data;
    return Promise.resolve()
  }

  destroy(key) {
    delete this.storage[key]
    return Promise.resolve()
  }

  storeList(list) {
    list.forEach(({ key, data }) => this.store(key, data));

    return Promise.resolve()
  }

  destroyStartedWith(beginningOfKey) {
    if(!beginningOfKey) return Promise.resolve()

    return this.list()
      .then(keysList => {
        const mask = new RegExp(`^${beginningOfKey}`)

        const keysForDeleting = keysList.filter(key => mask.test(key));
        keysForDeleting.forEach(deletingKey => this.destroy(deletingKey));
        //keysForDeleting.forEach(this.destroy, this);

        return Promise.resolve()
      })
  }

  fetchInTimeOrFail(key, timeout) {
    return new Promise((resolve, reject) => {
      this.fetch(key).then(resolve)
      setTimeout(() => reject('Item with this key not found'), timeout)
    })
  }
}

//--------------------------CREATING--------------------------//

const storage = new Storage();

//------------------------ADDING_ITEMS------------------------//

storage.store('boom', 'hallay');
storage.store('doom', 'Quake');
storage.store('cyka', 'Blyad');

// storage.list().then(console.log);

//--------------------------FETCHING--------------------------//

storage.fetch('doom').then((res) => console.log(`fetch  ->   ${res}`));

storage.fetchInTimeOrFail('doom', 500)
  .then((res) => console.log(`fetchInTimeOrFail  ->   ${res}`))
  .catch((err) => console.log(`fetchInTimeOrFail  ->  ${err}`))

//------------------------MULTI_ADDING------------------------//

const list = [{ key: 'vova', data: 'super' }, { key: 'gavno', data: 'pidar' }];

storage.storeList(list)
  .then(() => storage.list())
  .then(console.log);

//-------------------DESTROY_BY_PART_OF_KEY-------------------//

  storage.destroyStartedWith('c')
  .then(() => storage.list())
  .then(console.log)
  .catch(console.log)