simpler handleRatingChange

src/app/books/dashboard/dashboard.component.html

@@ -3,7 +3,7 @@
 @for (b of books(); track b.isbn) {
 
   <app-book
-    (ratingChange)="handleRatingChange($event)"
+    (ratingChange)="handleRatingChange($event.isbn, $event.newRating)"
     [book]="b"
   />
 

src/app/books/dashboard/dashboard.component.ts

@@ -20,7 +20,17 @@ export class DashboardComponent {
     this.books.update(books => books.toReversed());
   }
 
-  handleRatingChange({ isbn, newRating }: { isbn: string, newRating: number }) {
-    this.books.update(books => books.map(b => b.isbn === isbn ? { ...b, rating: newRating } : b));
+  handleRatingChange(isbn: string, newRating: number) {
+    this.books.update(books =>
+      books.map(b => {
+        // if this is the book we want to update, set the new rating
+        if (b.isbn === isbn) {
+          return { ...b, rating: newRating };
+        } else {
+          // leave all other books in the list unchanged
+          return b;
+        }
+      })
+    );
   }
 }