https://github.com/pmndrs/react-use-measure

🙌 Utility to measure view bounds
https://github.com/pmndrs/react-use-measure

Last synced: about 1 month ago
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🙌 Utility to measure view bounds

• Host: GitHub
• URL: https://github.com/pmndrs/react-use-measure
• Owner: pmndrs
• License: mit
• Created: 2019-10-31T14:19:05.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2023-01-07T04:24:00.000Z (over 1 year ago)
• Last Synced: 2024-05-01T11:29:10.609Z (5 months ago)
• Language: TypeScript
• Homepage:
• Size: 2.93 MB
• Stars: 804
• Watchers: 11
• Forks: 30
• Open Issues: 61
• Metadata Files:
  • Readme: readme.md
  • License: LICENSE

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README

        


  



    yarn add react-use-measure

This small tool will measure the boundaries (for instance width, height, top, left) of a view you reference. It is reactive and responds to changes in size, window-scroll and nested-area-scroll.

### Why do we need this hook?

Because there is [no simple way](https://stackoverflow.com/questions/442404/retrieve-the-position-x-y-of-an-html-element) to just get relative view coordinates. Yes, there is getBoundingClientRect, but it does not work when your content sits inside scroll areas whose offsets are simply neglected (as well as page scroll). Worse, mouse coordinates are relative to the viewport (the visible rect that contains the page). There is no easy way, for instance, to know that the mouse hovers over the upper/left corner of an element. This hook solves it for you.

You can try a live demo here: https://codesandbox.io/s/musing-kare-4fblz

# Usage

```jsx

import useMeasure from 'react-use-measure'

function App() {

  const [ref, bounds] = useMeasure()

  // consider that knowing bounds is only possible *after* the view renders

  // so you'll get zero values on the first run and be informed later

  return 


}

```


# Api

```jsx

interface RectReadOnly {

  readonly x: number

  readonly y: number

  readonly width: number

  readonly height: number

  readonly top: number

  readonly right: number

  readonly bottom: number

  readonly left: number

}

type Options = {

  // Debounce events in milliseconds

  debounce?: number | { scroll: number; resize: number }

  // React to nested scroll changes, don't use this if you know your view is static

  scroll?: boolean

  // You can optionally inject a resize-observer polyfill

  polyfill?: { new (cb: ResizeObserverCallback): ResizeObserver }

  // Measure size using offsetHeight and offsetWidth to ignore parent scale transforms

  offsetSize?: boolean

}

useMeasure(

  options: Options = { debounce: 0, scroll: false }

): [React.MutableRefObject, RectReadOnly]

```

# ⚠️ Notes

### Resize-observer polyfills

This lib relies on resize-observers. If you need a polyfill you can either polute the `window` object or inject it cleanly using the config options. We recommend [@juggle/resize-observer](https://github.com/juggle/resize-observer).

```jsx

import { ResizeObserver } from '@juggle/resize-observer'

function App() {

  const [ref, bounds] = useMeasure({ polyfill: ResizeObserver })

```

### Multiple refs

useMeasure currently returns its own ref. We do this because we are using functional refs for unmount tracking. If you need to have a ref of your own on the same element, use [react-merge-refs](https://github.com/smooth-code/react-merge-refs).