update adding demo app,

03_source/mobile/src/pages/store/FavouritesStore.js

@@ -0,0 +1,35 @@
+import { Store } from "pullstate";
+
+const FavouritesStore = new Store({
+    
+  favourites: []
+});
+
+export default FavouritesStore;
+
+export const checkIfFavourite = product => {
+
+	const currentFavourites = FavouritesStore.getRawState().favourites;
+  const isFavourite = currentFavourites.includes(product);
+
+	return isFavourite;
+}
+
+export const addToFavourites = (product, category) => {
+
+	const currentFavourites = FavouritesStore.getRawState().favourites;
+	const added = !currentFavourites.includes(product);
+
+	FavouritesStore.update(s => {
+
+		if (!added) {
+				
+			s.favourites = currentFavourites.filter(current => current !== product);
+		} else {
+				
+			s.favourites = [ ...s.favourites, product ];
+		}
+	});
+
+	return added;
+}