react-resize-detector

What is react-resize-detector?

The react-resize-detector is a React component designed to handle resize events for React elements. It provides a simple and efficient way to trigger a function or render logic when the size of an element changes. This is particularly useful in responsive designs and when elements need to adjust based on their container's dimensions.

What are react-resize-detector's main functionalities?

Basic resize detection

This feature allows you to detect the size of a component and react to changes. The `useResizeDetector` hook provides `width`, `height`, and `ref` which you attach to the component you want to monitor. The component re-renders whenever the size changes, displaying the new dimensions.

import React from 'react';
import useResizeDetector from 'react-resize-detector';

const ResponsiveComponent = () => {
  const { width, height, ref } = useResizeDetector();
  return (
    <div ref={ref}>
      Size: {width} x {height}
    </div>
  );
};

export default ResponsiveComponent;

OnResize callback

This feature uses the `withResizeDetector` higher-order component to monitor size changes. It provides `width`, `height`, and an `onResize` callback that is triggered on every resize event. This is useful for performing actions or calculations based on the new size.

import React from 'react';
import { withResizeDetector } from 'react-resize-detector';

class MyComponent extends React.Component {
  render() {
    const { width, height, onResize } = this.props;
    return (
      <div onResize={onResize}>
        Current size: {width} x {height}
      </div>
    );
  }
}

export default withResizeDetector(MyComponent, {
  handleWidth: true,
  handleHeight: true,
  onResize: (width, height) => console.log(`Resized to ${width} x ${height}`)
});

Other packages similar to react-resize-detector

react-sizeme

react-sizeme is another package that provides similar functionality to react-resize-detector. It allows components to respond to changes in size. However, react-sizeme uses a higher-order component approach primarily, which might be less convenient than hooks provided by react-resize-detector in functional components.

resize-observer-polyfill

This package is a polyfill for the ResizeObserver API, which is used to report changes to the dimensions of an Element's content or border box. It's more of a low-level API compared to react-resize-detector, which provides React-specific abstractions and hooks for easier integration in React applications.

README

Handle element resizes like it's 2021!

Live demo

Nowadays browsers support element resize handling natively using ResizeObservers. The library uses these observers to help you handle element resizes in React.

🐥 Tiny ~3kb

🐼 Written in TypeScript

🦁 Supports Function and Class Components

🐠 Used by 20k+ repositories

🦄 Generating 35M+ downloads/year

No window.resize listeners! No timeouts! No 👑 viruses! :)

TypeScript-lovers notice: starting from v6.0.0 you may safely remove @types/react-resize-detector from you deps list.

Installation

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

and

import ResizeObserver from 'react-resize-detector';

// or, in case you need to support some old browsers
import ResizeObserver from 'react-resize-detector/build/withPolyfill';

Examples

Starting from v6.0.0 there are 3 recommended ways to work with resize-detector library:

1. React hook (new in v6.0.0)

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

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

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

2. HOC pattern

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

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

export default withResizeDetector(CustomComponent);

3. Child Function Pattern

import ReactResizeDetector from 'react-resize-detector';

// ...

<ReactResizeDetector handleWidth handleHeight>
  {({ width, height }) => <div>{`${width}x${height}`}</div>}
</ReactResizeDetector>;

Full example (Class Component)

import React, { Component } from 'react';
import { withResizeDetector } from 'react-resize-detector';

const containerStyles = {
  height: '100vh',
  display: 'flex',
  alignItems: 'center',
  justifyContent: 'center'
};

class AdaptiveComponent extends Component {
  state = {
    color: 'red'
  };

  componentDidUpdate(prevProps) {
    const { width } = this.props;

    if (width !== prevProps.width) {
      this.setState({
        color: width > 500 ? 'coral' : 'aqua'
      });
    }
  }

  render() {
    const { width, height } = this.props;
    const { color } = this.state;
    return <div style={{ backgroundColor: color, ...containerStyles }}>{`${width}x${height}`}</div>;
  }
}

const AdaptiveWithDetector = withResizeDetector(AdaptiveComponent);

const App = () => {
  return (
    <div>
      <p>The rectangle changes color based on its width</p>
      <AdaptiveWithDetector />
    </div>
  );
};

export default App;

Full example (Functional Component)

import React, { useState, useEffect } from 'react';
import { withResizeDetector } from 'react-resize-detector';

const containerStyles = {
  height: '100vh',
  display: 'flex',
  alignItems: 'center',
  justifyContent: 'center'
};

const AdaptiveComponent = ({ width, height }) => {
  const [color, setColor] = useState('red');

  useEffect(() => {
    setColor(width > 500 ? 'coral' : 'aqua');
  }, [width]);

  return <div style={{ backgroundColor: color, ...containerStyles }}>{`${width}x${height}`}</div>;
};

const AdaptiveWithDetector = withResizeDetector(AdaptiveComponent);

const App = () => {
  return (
    <div>
      <p>The rectangle changes color based on its width</p>
      <AdaptiveWithDetector />
    </div>
  );
};

export default App;

We still support other ways to work with this library, but in the future consider using the ones described above. Please let me know if the examples above don't fit your needs.

Performance optimization

This library uses the native ResizeObserver API.

DOM nodes get attached to ResizeObserver.observe every time the component mounts and every time any property gets changed.

It means you should try to avoid passing anonymous functions to ResizeDetector, because they will trigger the whole initialization process every time the component rerenders. Use useCallback whenever it's possible.

// WRONG - anonymous function
const { ref, width, height } = useResizeDetector({
  onResize: () => {
    // on resize logic
  }
});

// CORRECT - `useCallback` approach
const onResize = useCallback(() => {
  // on resize logic
}, []);

const { ref, width, height } = useResizeDetector({ onResize });

Refs

The below explanation doesn't apply to useResizeDetector

The library is trying to be smart and does not add any extra DOM elements to not break your layouts. That's why we use findDOMNode method to find and attach listeners to the existing DOM elements. Unfortunately, this method has been deprecated and throws a warning in StrictMode.

For those who want to avoid this warning, we are introducing an additional property - targetRef. You have to set this prop as a ref of your target DOM element and the library will use this reference instead of searching the DOM element with help of findDOMNode

HOC pattern example

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

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

export default withResizeDetector(CustomComponent);

Child Function Pattern example

import ReactResizeDetector from 'react-resize-detector';

// ...

<ReactResizeDetector handleWidth handleHeight>
  {({ width, height, targetRef }) => <div ref={targetRef}>{`${width}x${height}`}</div>}
</ReactResizeDetector>;

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', () => {
  // [...]
});

License

MIT

❤️

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