@ng-web-apis/resize-observer

Resize Observer API for Angular

This is a library for declarative use of Resize Observer API with Angular.

Install

If you do not have @ng-web-apis/common:

npm i @ng-web-apis/common

Now install the package:

npm i @ng-web-apis/resize-observer

Usage

• Import WaResizeObserver
• Use waResizeObserver directive to observe an element:

<section>
  <h1
    waResizeBox="content-box"
    (waResizeObserver)="onResize($event)"
  >
    I'm being observed
  </h1>
</section>

Use waResizeBox to configure ResizeObserver options

NOTE: Keep in mind these are used one time in constructor so you cannot use binding, only strings.

Service

Alternatively you can use Observable-based ResizeObserverService and provide token RESIZE_OPTION_BOX manually:

@Component({
  selector: 'my-component',
  providers: [
    ResizeObserverService,
    {
      provide: RESIZE_OPTION_BOX,
      useValue: 'border-box',
    },
  ],
})
export class Example {
  constructor(@Inject(ResizeObserverService) entries$: ResizeObserverService) {
    entries$.subscribe((entries) => {
      // This will trigger when the component resizes
      // Don't forget to unsubscribe
      console.log(entries);
    });
  }
}

Browser support

79+	69+	64+	13.1+	13.4+

You can use polyfill to support older browsers

Demo

You can try online demo here

See also

Other Web APIs for Angular by @ng-web-apis

Changelog

4.12.0 (2025-03-28)

🚀 Features

• mutation-observer: add provideMutationObserverInit (#1198) (df39965)