Store ngrx initial state read via a promise in indexedDb

medium-ngrx-indexedb-bootstrap.ts

@Injectable()
export class AccountReducer {
  private initialState: AccountState
...
  bootstrap(): Promise<AccountState> {
    return new Promise(resolve =>
      // rehydrate uses indexedDb to read the state
      this.rehydrate(this.storage).subscribe(initialState => {
        this.initialState = initialState
        resolve()
      })
    )
  }
...
}