refactor(docs-infra): improve API reference page loading time and drop blocking time (#58911)

By scheduling the focus of the input, we can drop the blocking time that is caused by the blocking task of rendering.

PR Close #58911

adev/src/app/features/references/api-reference-list/api-reference-list.component.ts

@@ -16,7 +16,7 @@ import {
   model,
   signal,
   viewChild,
-  afterRenderEffect,
+  afterNextRender,
 } from '@angular/core';
 import ApiItemsSection from '../api-items-section/api-items-section.component';
 import {FormsModule} from '@angular/forms';
@@ -56,14 +56,14 @@ export default class ApiReferenceList {
   filterInput = viewChild.required(TextField, {read: ElementRef});
 
   constructor() {
-    afterRenderEffect({
-      write: () => {
-        // Lord forgive me for I have sinned
-        // Use the CVA to focus when https://github.com/angular/angular/issues/31133 is implemented
-        if (matchMedia('(hover: hover) and (pointer:fine)').matches) {
+    afterNextRender(() => {
+      // Lord forgive me for I have sinned
+      // Use the CVA to focus when https://github.com/angular/angular/issues/31133 is implemented
+      if (matchMedia('(hover: hover) and (pointer:fine)').matches) {
+        scheduleOnIdle(() => {
           this.filterInput().nativeElement.querySelector('input').focus();
-        }
-      },
+        });
+      }
     });
 
     effect(() => {
@@ -107,3 +107,16 @@ export default class ApiReferenceList {
     this.type.update((currentType) => (currentType === itemType ? ALL_STATUSES_KEY : itemType));
   }
 }
+
+/**
+ * Schedules a function to be run in a new macrotask.
+ * This is needed because the `requestIdleCallback` API is not available in all browsers.
+ * @param fn
+ */
+function scheduleOnIdle(fn: () => void): void {
+  if (typeof requestIdleCallback !== 'undefined') {
+    requestIdleCallback(fn);
+  } else {
+    setTimeout(fn, 0);
+  }
+}