fix(): overlays now present correctly when using custom elements build (#23039)

resolves #23029

core/src/utils/helpers.ts

@@ -5,11 +5,23 @@ import { Side } from '../interface';
 declare const __zone_symbol__requestAnimationFrame: any;
 declare const requestAnimationFrame: any;
 
+/**
+ * Waits for a component to be ready for
+ * both custom element and non-custom element builds.
+ * If non-custom element build, el.componentOnReady
+ * will be used.
+ * For custom element builds, we wait a frame
+ * so that the inner contents of the component
+ * have a chance to render.
+ *
+ * Use this utility rather than calling
+ * el.componentOnReady yourself.
+ */
 export const componentOnReady = (el: any, callback: any) => {
   if (el.componentOnReady) {
-    el.componentOnReady().then(callback);
+    el.componentOnReady().then((resolvedEl: any) => callback(resolvedEl));
   } else {
-    callback();
+    raf(() => callback(el));
   }
 }
 

core/src/utils/test/ready.spec.ts

@@ -0,0 +1,42 @@
+import { componentOnReady } from '../helpers';
+
+describe('componentOnReady()', () => {
+  it('should correctly call callback for a custom element', (done) => {
+    customElements.define('hello-world', class extends HTMLElement {
+      constructor() {
+        super();
+      }
+    });
+
+    const component = document.createElement('hello-world');
+    componentOnReady(component, (el) => {
+      expect(el).toBe(component);
+      done();
+    })
+  });
+
+  it('should correctly call callback for a lazy loaded component', (done) => {
+    const cb = jest.fn((el) => {
+      return new Promise((resolve) => {
+        setTimeout(() => resolve(el), 250);
+      });
+    });
+
+    customElements.define('hello-world', class extends HTMLElement {
+      constructor() {
+        super();
+      }
+
+      componentOnReady() {
+        return cb(this);
+      }
+    });
+
+    const component = document.createElement('hello-world');
+    componentOnReady(component, (el) => {
+      expect(el).toBe(component);
+      expect(cb).toHaveBeenCalledTimes(1);
+      done();
+    })
+  });
+});