Allow passing array of targets to delay

src/delay/delay.test.ts

@@ -234,3 +234,49 @@ test('double delay effect', async () => {
     ]
   `);
 });
+
+test('delay with array of units', async () => {
+  expect.assertions(2);
+
+  const source = createEvent();
+
+  const fnA = jest.fn();
+  const targetA = createEvent();
+
+  targetA.watch(fnA);
+
+  const fnB = jest.fn();
+  const targetB = createEvent();
+
+  targetB.watch(fnB);
+
+  delay({ source, timeout: 100, target: [targetA, targetB] });
+
+  source(1);
+
+  await waitFor(targetA);
+
+  expect(fnA).toHaveBeenCalledTimes(1);
+  expect(fnB).toHaveBeenCalledTimes(1);
+});
+
+test('delay throws when any of targets is not a unit', async () => {
+  expect.assertions(1);
+
+  const source = createEvent();
+  const target = createEvent();
+
+  expect(() =>
+    delay({ source, timeout: 100, target: [target, 'not a unit'] }),
+  ).toThrowError(/target must be a unit/);
+});
+
+test('delay throws when source is not a unit', async () => {
+  expect.assertions(1);
+
+  const target = createEvent();
+
+  expect(() => delay({ source: 'not a unit', timeout: 100, target })).toThrowError(
+    /source must be a unit/,
+  );
+});

src/delay/index.ts

@@ -1,39 +1,54 @@
 import {
   createEffect,
   createEvent,
-  forward,
   is,
   sample,
   Unit,
-  Event,
   Store,
-  Effect,
+  EventAsReturnType,
   combine,
+  Target as TargetType,
+  MultiTarget,
+  UnitValue,
 } from 'effector';
 
-type EventAsReturnType<Payload> = any extends Payload ? Event<Payload> : never;
+type TimeoutType<Payload> = ((payload: Payload) => number) | Store<number> | number;
 
-export function delay<T>({
+export function delay<Source extends Unit<any>, Target extends TargetType>(config: {
+  source: Source;
+  timeout: TimeoutType<UnitValue<Source>>;
+  target: MultiTarget<Target, UnitValue<Source>>;
+}): Target;
+
+export function delay<Source extends Unit<any>>(config: {
+  source: Source;
+  timeout: TimeoutType<UnitValue<Source>>;
+}): EventAsReturnType<UnitValue<Source>>;
+
+export function delay<
+  Source extends Unit<any>,
+  Target extends TargetType = TargetType,
+>({
   source,
   timeout,
-  target = createEvent<T>(),
+  target = createEvent() as any,
 }: {
-  source: Unit<T>;
-  timeout: ((_payload: T) => number) | Store<number> | number;
-  target?:
-    | Store<T>
-    | Event<T>
-    | Effect<T, any, any>
-    | Event<void>
-    | Effect<void, any, any>;
-}): EventAsReturnType<T> {
-  if (!is.unit(source)) throw new TypeError('source must be a unit from effector');
+  source: Source;
+  timeout: TimeoutType<UnitValue<Source>>;
+  target?: MultiTarget<Target, UnitValue<Source>>;
+}): typeof target extends undefined ? EventAsReturnType<UnitValue<Source>> : Target {
+  const targets = Array.isArray(target) ? target : [target];
 
-  if (!is.unit(target)) throw new TypeError('target must be a unit from effector');
+  if (!is.unit(source)) throw new TypeError('source must be a unit from effector');
+  if (!targets.every((unit) => is.unit(unit)))
+    throw new TypeError('target must be a unit from effector');
 
   const ms = validateTimeout(timeout);
 
-  const timerFx = createEffect<{ payload: T; milliseconds: number }, T>(
+  const timerFx = createEffect<
+    { payload: UnitValue<Source>; milliseconds: number },
+    UnitValue<Source>
+  >(
     ({ payload, milliseconds }) =>
       new Promise((resolve) => {
         setTimeout(resolve, milliseconds, payload);
@@ -44,7 +59,7 @@ export function delay<T>({
     // ms can be Store<number> | number
     // converts object of stores or object of values to store
     source: combine({ milliseconds: ms }),
-    clock: source,
+    clock: source as Unit<any>,
     fn: ({ milliseconds }, payload) => ({
       payload,
       milliseconds:
@@ -53,10 +68,9 @@ export function delay<T>({
     target: timerFx,
   });
 
-  // @ts-expect-error
-  forward({ from: timerFx.doneData, to: target });
+  sample({ clock: timerFx.doneData, target: targets as Unit<any>[] });
 
-  return timerFx.doneData;
+  return target as any;
 }
 
 function validateTimeout<T>(

src/delay/readme.md

@@ -20,11 +20,11 @@ target = delay({ source, timeout: number, target });
 
 1. `source` `(Event<T>` | `Store<T>` | `Effect<T>)` — Source unit, data from this unit used to trigger `target` with.
 1. `timeout` `(number)` — time to wait before trigger `event`
-1. `target` `(Event<T>` | `Store<T>` | `Effect<T`>)` — Optional. Target unit, that should be called after delay.
+1. `target` `(Unit<T>` | `Array<Unit<T>>)` — Optional. Target unit or array of units that will be called after delay.
 
 ### Returns
 
-- `event` `(Event<T>)` — New event, that triggered after delay
+- `target` `(Unit<T>` | `Array<Unit<T>>)` — Target unit or units that were passed to `delay`
 
 ### Example
 
@@ -61,7 +61,11 @@ target = delay({ source, timeout: Function, target });
 
 1. `source` `(Event<T>` | `Store<T>` | `Effect<T>)` — Source unit, data from this unit used to trigger `target` with.
 1. `timeout` `((payload: T) => number)` — Calculate delay for each `source` call. Receives the payload of `source` as argument. Should return `number` — delay in milliseconds.
-1. `target` `(Event<T>` | `Store<T>` | `Effect<T`>)` — Optional. Target unit, that should be called after delay.
+1. `target` `(Unit<T>` | `Array<Unit<T>>)` — Optional. Target unit or array of units that will be called after delay.
+
+### Returns
+
+- `target` `(Unit<T>` | `Array<Unit<T>>)` — Target unit or units that were passed to `delay`
 
 ### Example
 
@@ -109,7 +113,11 @@ target = delay({ source, timeout: $store, target });
 
 1. `source` `(Event<T>` | `Store<T>` | `Effect<T>)` — Source unit, data from this unit used to trigger `target` with.
 1. `timeout` `(Store<number>)` — Store with number — delay in milliseconds.
-1. `target` `(Event<T>` | `Store<T>` | `Effect<T`>)` — Optional. Target unit, that should be called after delay.
+1. `target` `(Unit<T>` | `Array<Unit<T>>)` — Optional. Target unit or array of units that will be called after delay.
+
+### Returns
+
+- `target` `(Unit<T>` | `Array<Unit<T>>)` — Target unit or units that were passed to `delay`
 
 ### Example
 

test-typings/delay.ts

@@ -1,5 +1,5 @@
 import { expectType } from 'tsd';
-import { Event, createStore, createEvent, createEffect } from 'effector';
+import { Event, createStore, createEvent, createEffect, Store } from 'effector';
 import { delay } from '../src/delay';
 
 // Check valid type for source
@@ -90,13 +90,138 @@ import { delay } from '../src/delay';
   const source = createEvent<number>();
   const target = createEvent();
 
-  expectType<Event<number>>(delay({ source, timeout: 100, target }));
+  expectType<typeof target>(delay({ source, timeout: 100, target }));
 }
 
 // void effects support
 {
   const source = createEvent<number>();
   const target = createEffect<void, void>();
 
-  expectType<Event<number>>(delay({ source, timeout: 100, target }));
+  expectType<typeof target>(delay({ source, timeout: 100, target }));
+}
+
+// supports wider type in target
+{
+  const source = createEvent<number>();
+  const target = createEvent<number | string>();
+
+  delay({ source, timeout: 100, target });
+}
+
+// does not allow narrower type in target
+{
+  const source = createEvent<number>();
+  const target = createEvent<1 | 2>();
+
+  delay({
+    source,
+    timeout: 100,
+    // @ts-expect-error
+    target,
+  });
+}
+
+// supports multiple targets as an array
+{
+  const source = createStore<string>('');
+
+  const $targetStore = createStore<string>('');
+
+  const targetEvent = createEvent<string>();
+  const targetEventVoid = createEvent<void>();
+
+  const targetEffect = createEffect<string, void>();
+  const targetEffectVoid = createEffect<void, void>();
+
+  delay({
+    source,
+    timeout: 100,
+    target: [
+      $targetStore,
+      targetEvent,
+      targetEventVoid,
+      targetEffect,
+      targetEffectVoid,
+    ],
+  });
+}
+
+// does not allow invalid targets in array
+{
+  const source = createStore<string>('');
+
+  // @ts-expect-error
+  delay({ source, timeout: 100, target: ['non-unit'] });
+  // @ts-expect-error
+  delay({ source, timeout: 100, target: [null] });
+  // @ts-expect-error
+  delay({ source, timeout: 100, target: [100] });
+  // @ts-expect-error
+  delay({ source, timeout: 100, target: [() => ''] });
+}
+
+// does not allow incompatible targets in array
+{
+  const source = createStore<string>('');
+
+  // @ts-expect-error
+  delay({
+    source,
+    timeout: 100,
+    target: [createEvent<number>()],
+  });
+
+  // @ts-expect-error
+  delay({
+    source,
+    timeout: 100,
+    target: [createEffect<number, void>()],
+  });
+
+  // @ts-expect-error
+  delay({
+    source,
+    timeout: 100,
+    target: [createStore<number>(0)],
+  });
+
+  delay({
+    source,
+    timeout: 100,
+    // @ts-expect-error
+    target: [
+      createEvent<number>(),
+      createEffect<number, void>(),
+      createStore<number>(0),
+    ],
+  });
+
+  // @ts-expect-error
+  delay({
+    source,
+    timeout: 100,
+    target: [createEvent<string>(), 'non-unit'],
+  });
+}
+
+// returns typeof target
+{
+  const source = createStore<'x'>('x');
+
+  expectType<Event<'x'>>(
+    delay({
+      source,
+      timeout: 100,
+      target: createEvent<'x'>(),
+    }),
+  );
+
+  expectType<[Event<'x'>, Store<string>, Event<string>]>(
+    delay({
+      source,
+      timeout: 100,
+      target: [createEvent<'x'>(), createStore<string>(''), createEvent<string>()],
+    }),
+  );
 }