docs(signals): mention re-use of withComputed/withMethods (#4780)

Closes #4669

Co-authored-by: Marko Stanimirović <[email protected]>

Author: michael-small

projects/ngrx.io/content/guide/signals/faq.md

@@ -75,3 +75,29 @@ export class Counter {
 }
 ```
 </details>
+
+<details>
+  <summary><b>#6</b> Can features like `withComputed` or `withMethods` reference other members inside the same feature?</summary>
+
+It may be necessary for a computed in a `withComputed` feature to need to reference another computed value, 
+or a method in a `withMethods` feature to refer to another method. To do so, you can break out the common piece 
+with a helper that can serve as a function or computed itself. 
+
+Although it is possible to have multiple features that reference each other, we recommend having everything in one call. 
+That adheres more to JavaScript's functional style and keeps features co-located.
+
+```ts
+export const BooksStore = signalStore(
+  withState(initialState),
+  withComputed(({ filter }) => {
+    // 👇 Define helper functions (or computed signals).
+    const sortDirection = computed(() => (filter.order() === 'asc' ? 1 : -1));
+
+    return {
+      sortDirection,
+      sortDirectionReversed: () => sortDirection() * -1,
+    };
+  })
+);
+```
+</details>

projects/www/src/app/pages/guide/signals/faq.md

@@ -1,7 +1,7 @@
 # Frequently Asked Questions
 
 <details>
-  <summary>How to connect my SignalStore(s) with Redux DevTools?</summary>
+  <summary><b>#1</b> How to connect my SignalStore(s) with Redux DevTools?</summary>
 
 There's no official connection between `@ngrx/signals` and the Redux Devtools.
 We expect the Angular Devtools will provide support for signals soon, which can be used to track the state.
@@ -10,7 +10,7 @@ However, you could create a feature for this, or you can make use of the [`withD
 </details>
 
 <details>
-  <summary>Can I use the Flux/Redux pattern with SignalStore?</summary>
+  <summary><b>#2</b> Can I use the Flux/Redux pattern with SignalStore?</summary>
 
 Yes. Starting from NgRx version 19.2, the Events plugin introduces support for a Flux-style state management with SignalStore.
 It enables defining and dispatching events, handling them through reducers and effects, and maintaining a unidirectional data flow similar to the traditional Redux pattern.
@@ -19,7 +19,7 @@ For more information, see the Events Plugin documentation.
 </details>
 
 <details>
-  <summary>Can I define my SignalStore as a class?</summary>
+  <summary><b>#3</b> Can I define my SignalStore as a class?</summary>
 
 Yes, it is possible to define a SignalStore using a class-based approach.
 However, the NgRx team recommends using the functional style for defining SignalStores.
@@ -43,7 +43,7 @@ export class CounterStore extends signalStore(
 </details>
 
 <details>
-  <summary>How can I get the type of a SignalStore?</summary>
+  <summary><b>#4</b> How can I get the type of a SignalStore?</summary>
 
 To get the type of a SignalStore, use the `InstanceType` utility type.
 
@@ -60,7 +60,7 @@ function logCount(store: CounterStore): void {
 </details>
 
 <details>
-  <summary>Can I inject a SignalStore via the constructor?</summary>
+  <summary><b>#5</b> Can I inject a SignalStore via the constructor?</summary>
 
 Yes. To inject a SignalStore via the constructor, define and export its type with the same name.
 
@@ -82,3 +82,32 @@ export class Counter {
 ```
 
 </details>
+
+<details>
+  <summary><b>#6</b> Can features like `withComputed` or `withMethods` reference other members inside the same feature?</summary>
+
+It may be necessary for a computed in a `withComputed` feature to need to reference another computed value,
+or a method in a `withMethods` feature to refer to another method. To do so, you can break out the common piece
+with a helper that can serve as a function or computed itself.
+
+Although it is possible to have multiple features that reference each other, we recommend having everything in one call.
+That adheres more to JavaScript's functional style and keeps features co-located.
+
+```ts
+export const BooksStore = signalStore(
+  withState(initialState),
+  withComputed(({ filter }) => {
+    // 👇 Define helper functions (or computed signals).
+    const sortDirection = computed(() =>
+      filter.order() === 'asc' ? 1 : -1
+    );
+
+    return {
+      sortDirection,
+      sortDirectionReversed: () => sortDirection() * -1,
+    };
+  })
+);
+```
+
+</details>