feat(utils): createKeyedSignal key/value overload

Author: josepot

packages/utils/src/createKeyedSignal.spec.ts

@@ -42,6 +42,57 @@ describe("createKeyedSignal", () => {
     subscription2.unsubscribe()
   })
 
+  it("receives a key selector and returns a tuple with an observable-getter and its corresponding event-emitter", () => {
+    const [getFooBar$, onFooBar] = createKeyedSignal(
+      (signal: { key: string; foo: number; bar: string }) => signal.key,
+    )
+
+    let receivedValue1
+    let nHits1 = 0
+    const subscription1 = getFooBar$("key").subscribe((val) => {
+      receivedValue1 = val
+      nHits1++
+    })
+
+    expect(receivedValue1).toBe(undefined)
+    onFooBar({ key: "key", foo: 0, bar: "1" })
+    expect(receivedValue1).toEqual({ foo: 0, bar: "1", key: "key" })
+    expect(nHits1).toBe(1)
+
+    let receivedValue2
+    let nHits2 = 0
+    const subscription2 = getFooBar$("key").subscribe((val) => {
+      receivedValue2 = val
+      nHits2++
+    })
+
+    expect(receivedValue2).toBe(undefined)
+
+    onFooBar({ key: "key", foo: 1, bar: "2" })
+    expect(receivedValue1).toEqual({ foo: 1, bar: "2", key: "key" })
+    expect(nHits1).toBe(2)
+    expect(receivedValue2).toEqual({ foo: 1, bar: "2", key: "key" })
+    expect(nHits2).toBe(1)
+
+    onFooBar({ key: "key2", foo: 1, bar: "2" })
+    expect(nHits1).toBe(2)
+    expect(nHits2).toBe(1)
+
+    subscription1.unsubscribe()
+    subscription2.unsubscribe()
+  })
+
+  it("returns a tupe with a typed observable and its corresponding event-emitter for the key-value overload", () => {
+    const [foo$, onFoo] = createKeyedSignal<string, number>()
+    let receivedValue
+    foo$("foo").subscribe((val) => {
+      receivedValue = val
+    })
+    expect(receivedValue).toBe(undefined)
+    onFoo("foo", 5)
+    expect(receivedValue).toEqual(5)
+  })
+
   it('returns a tuple with a typed observable and its corresponding event-emitter when no "event creator" is provided', () => {
     const [foo$, onFoo] = createKeyedSignal<string>()
     let receivedValue

packages/utils/src/createKeyedSignal.ts

@@ -1,4 +1,4 @@
-import { GroupedObservable, identity, Observable, Observer } from "rxjs"
+import { GroupedObservable, Observable, Observer } from "rxjs"
 
 /**
  * Creates a "keyed" signal. It's sugar for splitting the Observer and the Observable of a keyed signal.
@@ -20,7 +20,20 @@ export function createKeyedSignal<T>(): [
  * 1. The getter function that returns the GroupedObservable<K, T>
  * 2. The emitter function.
  */
-export function createKeyedSignal<T, K, A extends any[]>(
+export function createKeyedSignal<K, T>(): [
+  (key: K) => GroupedObservable<K, T>,
+  (key: K, value: T) => void,
+]
+
+/**
+ * Creates a "keyed" signal. It's sugar for splitting the Observer and the Observable of a keyed signal.
+ *
+ * @param keySelector a function that extracts the key from the emitted value
+ * @returns [1, 2]
+ * 1. The getter function that returns the GroupedObservable<K, T>
+ * 2. The emitter function.
+ */
+export function createKeyedSignal<K, T>(
   keySelector: (signal: T) => K,
 ): [(key: K) => GroupedObservable<K, T>, (signal: T) => void]
 
@@ -33,14 +46,14 @@ export function createKeyedSignal<T, K, A extends any[]>(
  * 1. The getter function that returns the GroupedObservable<K, T>
  * 2. The emitter function (...args: any[]) => T.
  */
-export function createKeyedSignal<T, K, A extends any[]>(
+export function createKeyedSignal<K, T, A extends any[]>(
   keySelector: (signal: T) => K,
   mapper: (...args: A) => T,
 ): [(key: K) => GroupedObservable<K, T>, (...args: A) => void]
 
-export function createKeyedSignal<T, K, A extends any[]>(
-  keySelector: (signal: T) => K = identity as any,
-  mapper: (...args: A) => T = identity as any,
+export function createKeyedSignal<K, T, A extends any[]>(
+  keySelector?: (signal: T) => K,
+  mapper?: (...args: A) => T,
 ): [(key: K) => GroupedObservable<K, T>, (...args: A) => void] {
   const observersMap = new Map<K, Set<Observer<T>>>()
 
@@ -63,8 +76,13 @@ export function createKeyedSignal<T, K, A extends any[]>(
       return res
     },
     (...args: A) => {
-      const payload = mapper(...args)
-      observersMap.get(keySelector(payload))?.forEach((o) => {
+      const payload = mapper
+        ? mapper(...args)
+        : args.length === 2
+        ? args[1]
+        : args[0]
+      const key = keySelector ? keySelector(payload) : args[0]
+      observersMap.get(key)?.forEach((o) => {
         o.next(payload)
       })
     },