Learn TypeScript 3 by Building Web Applications

Service implementation

First of all, we need to import localForage in our code:

1. Add the following statement at the top of the file in order to import localForage: import localForage from "localforage";. Without this, you will not be able to use the library. By doing this, we will actually trigger loading localForage when our JavaScript code gets loaded by the index.html file.
2. Now that we have added localForage and have loaded it, we can create an implementation of the MediaService interface:

class MediaServiceImpl<T extends Media> implements MediaService<T> { 
    loadMediaCollection(identifier: string):     Promise<MediaCollection<T>> { ... } 
    saveMediaCollection(collection: MediaCollection<T>):         Promise<void>  { ... } getMediaCollectionIdentifiersList(): ...