Learn TypeScript 3 by Building Web Applications

Implementing the reloadBookCollections method

Implement this method as follows:

reloadBookCollections(): void {    this._bookService.getMediaCollectionIdentifiersList().then(keys => {        this._bookCollections.clear(); // clear the current state        this._view.clearBookCollections(); // remove the DOM nodes        keys.forEach(key => {            this._bookService.loadMediaCollection(key).then(collection             => {                this._bookCollections.set(key, collection);                this._view.renderBookCollection(collection);            });        });    });}

This method relies on the book service to manage the collection and orchestrate the view.