import { Injectable } from '@angular/core'; import * as localForage from 'localforage'; @Injectable() export class LocalStorageService { getItem(key: string, callback: any): void { if (!localForage) { return; } localForage.getItem(key, callback); } setItem(key, value): void { if (!localForage) { return; } if (value === null) { value = undefined; } localForage.setItem(key, value); } }