Handle element resizes like it's 2024!

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 160k 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.

Example

<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` and `height` 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', () => {
  // [...]
});