React ResizeObserver Hook

---

Observe multiple DOM elements with a single ResizeObserver.

This package provides you with:

• a context <Provider> with a ResizeObserver instance;
• a useResizeObserver() hook to observe any element's size changes.

This allows you to know the size of each observed element.

📚 Docs

This package was developed and documented as part of the @envato/react-breakpoints package. It's separated into its own package because I believe it can be used separately if you don't need all the abstractions that React Breakpoints gives you. Please refer to the React Breakpoints API Docs for more details about <Provider> and useResizeObserver().

⚡️ Quick start

npm install @envato/react-resize-observer-hook

Set up the provider

import { Provider as ResizeObserverProvider } from '@envato/react-resize-observer-hook';

const App = () => <ResizeObserverProvider>...</ResizeObserverProvider>;

⚠️ Caution — You may need to pass some props to <Provider> to increase browser support. Please refer to the React Breakpoints API Docs.

Observe an element

import { useResizeObserver } from '@envato/react-resize-observer-hook';

const ObservedDiv = () => {
  const [ref, observedEntry] = useResizeObserver();
  const { width, height } = observedEntry.contentRect;

  return (
    <div ref={ref}>
      This element is {width}px wide and {height}px high.
    </div>
  );
};

Depending on your implementation of ResizeObserver, the internal ResizeObserverEntry can contain size information about multiple "boxes" of the observed element. Observing these boxes instead of contentRect (default) can be done by passing an options object to the hook:

const options = {
  box: 'border-box'
};

const [ref, observedEntry] = useResizeObserver(options);

const width = observedEntry.borderBox[0].inlineSize;
const height = observedEntry.borderBox[0].blockSize;

See MDN reference guide for further information.

Maintainers

• Marc Dingena (owner)

Contributing

For bug fixes, documentation changes, and small features:

1. Fork this repository.
2. Create your feature branch (git checkout -b my-new-feature).
3. Commit your changes (git commit -am 'Add some feature').
4. Push to the branch (git push origin my-new-feature).
5. Create a new Pull Request.

For larger new features: Do everything as above, but first also make contact with the project maintainers to be sure your change fits with the project direction and you won't be wasting effort going in the wrong direction.