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.

1<div class="post">
2  <div class="card">
3    <h2>Card title</h2>
4    <p>Card content</p>
5  </div>
6</div>

1.post {
2  container-type: inline-size;
3}
4
5/* Default heading styles for the card title */
6.card h2 {
7  font-size: 1em;
8}
9
10/* If the container is larger than 700px */
11@container (min-width: 700px) {
12  .card h2 {
13    font-size: 2em;
14  }
15}

Installation

1npm i react-resize-detector
2// OR
3yarn add react-resize-detector

Example

1import { useResizeDetector } from 'react-resize-detector';
2
3const CustomComponent = () => {
4  const { width, height, ref } = useResizeDetector();
5  return <div ref={ref}>{`${width}x${height}`}</div>;
6};

With props

1import { useResizeDetector } from 'react-resize-detector';
2
3const CustomComponent = () => {
4  const onResize = useCallback(() => {
5    // on resize logic
6  }, []);
7
8  const { width, height, ref } = useResizeDetector({
9    handleHeight: false,
10    refreshMode: 'debounce',
11    refreshRate: 1000,
12    onResize,
13  });
14
15  return <div ref={ref}>{`${width}x${height}`}</div>;
16};

With custom ref

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

1import { useResizeDetector } from 'react-resize-detector';
2
3const CustomComponent = () => {
4  const targetRef = useRef();
5  const { width, height } = useResizeDetector({ targetRef });
6  return <div ref={targetRef}>{`${width}x${height}`}</div>;
7};

API

Testing with Enzyme and Jest

Thanks to @Primajin for posting this snippet

1const { ResizeObserver } = window;
2
3beforeEach(() => {
4  delete window.ResizeObserver;
5  window.ResizeObserver = jest.fn().mockImplementation(() => ({
6    observe: jest.fn(),
7    unobserve: jest.fn(),
8    disconnect: jest.fn(),
9  }));
10
11  wrapper = mount(<MyComponent />);
12});
13
14afterEach(() => {
15  window.ResizeObserver = ResizeObserver;
16  jest.restoreAllMocks();
17});
18
19it('should do my test', () => {
20  // [...]
21});

License

MIT

❤️

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