useElementSize()

1import { useCallback, useState } from 'react'
2
3// See: https://usehooks-ts.com/react-hook/use-event-listener
4import { useEventListener } from '../useEventListener'
5// See: https://usehooks-ts.com/react-hook/use-isomorphic-layout-effect
6import { useIsomorphicLayoutEffect } from '../useIsomorphicLayoutEffect'
7
8interface Size {
9  width: number
10  height: number
11}
12
13function useElementSize<T extends HTMLElement = HTMLDivElement>(): [
14  (node: T | null) => void,
15  Size,
16] {
17  // Mutable values like 'ref.current' aren't valid dependencies
18  // because mutating them doesn't re-render the component.
19  // Instead, we use a state as a ref to be reactive.
20  const [ref, setRef] = useState<T | null>(null)
21  const [size, setSize] = useState<Size>({
22    width: 0,
23    height: 0,
24  })
25
26  // Prevent too many rendering using useCallback
27  const handleSize = useCallback(() => {
28    setSize({
29      width: ref?.offsetWidth || 0,
30      height: ref?.offsetHeight || 0,
31    })
32
33    // eslint-disable-next-line react-hooks/exhaustive-deps
34  }, [ref?.offsetHeight, ref?.offsetWidth])
35
36  useEventListener('resize', handleSize)
37
38  useIsomorphicLayoutEffect(() => {
39    handleSize()
40    // eslint-disable-next-line react-hooks/exhaustive-deps
41  }, [ref?.offsetHeight, ref?.offsetWidth])
42
43  return [setRef, size]
44}
45
46export default useElementSize

1import React, { useState } from 'react'
2
3import { useElementSize } from 'usehooks-ts'
4
5export default function Component() {
6  const [isVisible, setVisible] = useState(true)
7  const [squareRef, { width, height }] = useElementSize()
8
9  const toggleVisibility = () => setVisible(x => !x)
10
11  return (
12    <>
13      <p>{`The square width is ${width}px and height ${height}px`}</p>
14      <p>Try, resize your window and-or click on the button.</p>
15
16      <button onClick={toggleVisibility}>
17        {isVisible ? 'Hide' : 'Show'} square
18      </button>
19
20      {isVisible && (
21        <div
22          ref={squareRef}
23          style={{
24            width: '50%',
25            paddingTop: '50%',
26            backgroundColor: 'aquamarine',
27            margin: 'auto',
28          }}
29        />
30      )}
31    </>
32  )
33}