Handle element resizes like it's 2025!

Live demo

Modern browsers now have native support for detecting element size changes through ResizeObservers. This library utilizes ResizeObservers to facilitate managing element size changes in React applications.

🐥 Tiny ~2kb

🐼 Written in TypeScript

🐠 Used by 170k repositories

🦄 Produces 100 million downloads annually

No window.resize listeners! No timeouts!

Is it necessary for you to use this library?

Container queries now work in all major browsers. It's very likely you can solve your task using pure CSS.

<div class="post">
  <div class="card">
    <h2>Card title</h2>
    <p>Card content</p>
  </div>
</div>

.post {
  container-type: inline-size;
}

/* Default heading styles for the card title */
.card h2 {
  font-size: 1em;
}

/* If the container is larger than 700px */
@container (min-width: 700px) {
  .card h2 {
    font-size: 2em;
  }
}

Installation

npm i react-resize-detector
// OR
yarn add react-resize-detector

Example

import { useResizeDetector } from 'react-resize-detector';

const CustomComponent = () => {
  const { width, height, ref } = useResizeDetector();
  return <div ref={ref}>{`${width}x${height}`}</div>;
};

With props

import { useResizeDetector } from 'react-resize-detector';

const CustomComponent = () => {
  const onResize = useCallback(() => {
    // on resize logic
  }, []);

  const { width, height, ref } = useResizeDetector({
    handleHeight: false,
    refreshMode: 'debounce',
    refreshRate: 1000,
    onResize,
  });

  return <div ref={ref}>{`${width}x${height}`}</div>;
};

With custom ref

It's not advised to use this approach, as dynamically mounting and unmounting the observed element could lead to unexpected behavior.

import { useResizeDetector } from 'react-resize-detector';

const CustomComponent = () => {
  const targetRef = useRef();
  const { width, height } = useResizeDetector({ targetRef });
  return <div ref={targetRef}>{`${width}x${height}`}</div>;
};

API

| Prop | Type | Description | Default | | --------------- | ------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------- | | onResize | Func | Function that will be invoked with width, height and ResizeObserver entry arguments | undefined | | handleWidth | Bool | Trigger onResize on width change | true | | handleHeight | Bool | Trigger onResize on height change | true | | skipOnMount | Bool | Do not trigger onResize when a component mounts | false | | refreshMode | String | Possible values: throttle and debounce See lodash docs for more information. undefined - callback will be fired for every frame | undefined | | refreshRate | Number | Use this in conjunction with refreshMode. Important! It's a numeric prop so set it accordingly, e.g. refreshRate={500} | 1000 | | refreshOptions | Object | Use this in conjunction with refreshMode. An object in shape of { leading: bool, trailing: bool }. Please refer to lodash's docs for more info | undefined | | observerOptions | Object | These options will be used as a second parameter of resizeObserver.observe method. | undefined | | targetRef | Ref | Use this prop to pass a reference to the element you want to attach resize handlers to. It must be an instance of React.useRef or React.createRef functions | undefined |

Testing with Enzyme and Jest

Thanks to @Primajin for posting this snippet

const { ResizeObserver } = window;

beforeEach(() => {
  delete window.ResizeObserver;
  window.ResizeObserver = jest.fn().mockImplementation(() => ({
    observe: jest.fn(),
    unobserve: jest.fn(),
    disconnect: jest.fn(),
  }));

  wrapper = mount(<MyComponent />);
});

afterEach(() => {
  window.ResizeObserver = ResizeObserver;
  jest.restoreAllMocks();
});

it('should do my test', () => {
  // [...]
});

License

MIT

❤️

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