feat(template): add PLATFORM and effectOnceIf utilities

eneajaho · eneajaho · commit d892044bd7fa · 2026-01-31T22:33:03.000+01:00
Introduced `effectOnceIf`, enabling conditional execution of effects in Angular's DI context with cleanup and flexible options. Added new `PLATFORM` token for platform-specific feature detection.
diff --git a/libs/template/virtual-view/src/lib/util.ts b/libs/template/virtual-view/src/lib/util.ts
@@ -0,0 +1,52 @@
+import { isPlatformBrowser, isPlatformServer } from '@angular/common';
+import { DOCUMENT, inject, InjectionToken, PLATFORM_ID } from '@angular/core';
+
+export const PLATFORM = new InjectionToken('PLATFORM', {
+  providedIn: 'platform',
+  factory: () => {
+    const platformId = inject(PLATFORM_ID);
+    const document = inject(DOCUMENT);
+
+    const isServer = isPlatformServer(platformId);
+    const isBrowser = isPlatformBrowser(platformId);
+    const isServerRenderer = isBrowser && !!document.getElementById('ng-state');
+
+    return { isServer, isBrowser, isServerRenderer };
+  },
+});
+
+// https://ngxtension.dev/utilities/signals/effect-once-if/
+import {
+  CreateEffectOptions,
+  effect,
+  EffectCleanupRegisterFn,
+  EffectRef,
+  runInInjectionContext,
+  untracked,
+} from '@angular/core';
+import { assertInjector } from './assert-injector';
+
+export function effectOnceIf<T = any>(
+  condition: () => T,
+  execution: (
+    valueFromCondition: NonNullable<T>,
+    onCleanup: EffectCleanupRegisterFn,
+  ) => void,
+  options?: Omit<CreateEffectOptions, 'manualCleanup'>,
+): EffectRef {
+  const assertedInjector = assertInjector(effectOnceIf, options?.injector);
+  return runInInjectionContext(assertedInjector, () => {
+    const effectRef = effect((onCleanup) => {
+      const hasCondition = condition();
+      if (hasCondition) {
+        untracked(() => execution(hasCondition, onCleanup));
+        effectRef.destroy();
+      }
+    }, options);
+    return effectRef;
+  });
+}
+
+export type EffectOnceIfConditionFn<T> = Parameters<typeof effectOnceIf<T>>[0];
+export type EffectOnceIfExecutionFn<T> = Parameters<typeof effectOnceIf<T>>[1];
+export type EffectOnceIfOptions<T> = Parameters<typeof effectOnceIf<T>>[2];
