fix(component): use setTimeout instead of requestAnimationFrame in SSR mode

modules/component/spec/core/tick-scheduler.spec.ts

@@ -4,18 +4,24 @@ import {
   TestBed,
   tick,
 } from '@angular/core/testing';
-import { ApplicationRef, NgZone } from '@angular/core';
+import { ApplicationRef, NgZone, PLATFORM_ID } from '@angular/core';
 import {
-  AnimationFrameTickScheduler,
   NoopTickScheduler,
   TickScheduler,
+  ZonelessTickScheduler,
 } from '../../src/core/tick-scheduler';
 import { ngZoneMock, noopNgZoneMock } from '../fixtures/fixtures';
 
 describe('TickScheduler', () => {
-  function setup(ngZone: unknown) {
+  function setup(ngZone: unknown, isSsrMode = false) {
     TestBed.configureTestingModule({
-      providers: [{ provide: NgZone, useValue: ngZone }],
+      providers: [
+        { provide: NgZone, useValue: ngZone },
+        {
+          provide: PLATFORM_ID,
+          useValue: isSsrMode ? 'server' : 'browser',
+        },
+      ],
     });
     const tickScheduler = TestBed.inject(TickScheduler);
     const appRef = TestBed.inject(ApplicationRef);
@@ -31,16 +37,16 @@ describe('TickScheduler', () => {
     });
   });
 
-  describe('when NgZone is not provided', () => {
+  describe('when NgZone is not provided and running in browser mode', () => {
     // `fakeAsync` uses 16ms as `requestAnimationFrame` delay
     const animationFrameDelay = 16;
 
-    it('should initialize AnimationFrameTickScheduler', () => {
+    it('should initialize ZonelessTickScheduler', () => {
       const { tickScheduler } = setup(noopNgZoneMock);
-      expect(tickScheduler instanceof AnimationFrameTickScheduler).toBe(true);
+      expect(tickScheduler instanceof ZonelessTickScheduler).toBe(true);
     });
 
-    it('should schedule tick using the animationFrameScheduler', fakeAsync(() => {
+    it('should schedule tick using requestAnimationFrame', fakeAsync(() => {
       const { tickScheduler, appRef } = setup(noopNgZoneMock);
 
       tickScheduler.schedule();
@@ -87,4 +93,56 @@ describe('TickScheduler', () => {
       expect(appRef.tick).toHaveBeenCalledTimes(3);
     }));
   });
+
+  describe('when NgZone is not provided and running in SSR mode', () => {
+    it('should initialize ZonelessTickScheduler', () => {
+      const { tickScheduler } = setup(noopNgZoneMock, true);
+      expect(tickScheduler instanceof ZonelessTickScheduler).toBe(true);
+    });
+
+    it('should schedule tick using setTimeout', fakeAsync(() => {
+      const { tickScheduler, appRef } = setup(noopNgZoneMock, true);
+
+      tickScheduler.schedule();
+
+      expect(appRef.tick).toHaveBeenCalledTimes(0);
+      tick();
+      expect(appRef.tick).toHaveBeenCalledTimes(1);
+    }));
+
+    it('should coalesce multiple synchronous schedule calls', fakeAsync(() => {
+      const { tickScheduler, appRef } = setup(noopNgZoneMock, true);
+
+      tickScheduler.schedule();
+      tickScheduler.schedule();
+      tickScheduler.schedule();
+
+      tick();
+      expect(appRef.tick).toHaveBeenCalledTimes(1);
+    }));
+
+    it('should coalesce multiple schedule calls that are queued to the microtask queue', fakeAsync(() => {
+      const { tickScheduler, appRef } = setup(noopNgZoneMock, true);
+
+      queueMicrotask(() => tickScheduler.schedule());
+      queueMicrotask(() => tickScheduler.schedule());
+      queueMicrotask(() => tickScheduler.schedule());
+
+      flushMicrotasks();
+      expect(appRef.tick).toHaveBeenCalledTimes(0);
+      tick();
+      expect(appRef.tick).toHaveBeenCalledTimes(1);
+    }));
+
+    it('should schedule multiple ticks for multiple asynchronous schedule calls', fakeAsync(() => {
+      const { tickScheduler, appRef } = setup(noopNgZoneMock, true);
+
+      setTimeout(() => tickScheduler.schedule(), 100);
+      setTimeout(() => tickScheduler.schedule(), 200);
+      setTimeout(() => tickScheduler.schedule(), 300);
+
+      tick(300);
+      expect(appRef.tick).toHaveBeenCalledTimes(3);
+    }));
+  });
 });

modules/component/src/core/tick-scheduler.ts

@@ -1,4 +1,11 @@
-import { ApplicationRef, inject, Injectable, NgZone } from '@angular/core';
+import {
+  ApplicationRef,
+  inject,
+  Injectable,
+  NgZone,
+  PLATFORM_ID,
+} from '@angular/core';
+import { isPlatformServer } from '@angular/common';
 import { isNgZone } from './zone-helpers';
 
 @Injectable({
@@ -7,7 +14,7 @@ import { isNgZone } from './zone-helpers';
     const zone = inject(NgZone);
     return isNgZone(zone)
       ? new NoopTickScheduler()
-      : inject(AnimationFrameTickScheduler);
+      : inject(ZonelessTickScheduler);
   },
 })
 export abstract class TickScheduler {
@@ -17,17 +24,19 @@ export abstract class TickScheduler {
 @Injectable({
   providedIn: 'root',
 })
-export class AnimationFrameTickScheduler extends TickScheduler {
+export class ZonelessTickScheduler extends TickScheduler {
+  private readonly appRef = inject(ApplicationRef);
+  private readonly platformId = inject(PLATFORM_ID);
+  private readonly isServer = isPlatformServer(this.platformId);
+  private readonly scheduleFn = this.isServer
+    ? setTimeout
+    : requestAnimationFrame;
   private isScheduled = false;
 
-  constructor(private readonly appRef: ApplicationRef) {
-    super();
-  }
-
   schedule(): void {
     if (!this.isScheduled) {
       this.isScheduled = true;
-      requestAnimationFrame(() => {
+      this.scheduleFn(() => {
         this.appRef.tick();
         this.isScheduled = false;
       });