useLockedBody()

This React hook is used to block the scrolling of the page.

A good example of a use case is when you need to open a modal.

For flexibility, this hook offers 2 APIs:

Use it as we would use a useState (example 1)
Use it with our own logic, coming from a props or redux for example (example 2)

Finally, you can optionally change the reflow padding if you have another sidebar size than the default (15px)

The Hook

1import { useEffect, useState } from 'react'
2
3// See: https://usehooks-ts.com/react-hook/use-isomorphic-layout-effect
4import { useIsomorphicLayoutEffect } from '../useIsomorphicLayoutEffect'
5
6type ReturnType = [boolean, (locked: boolean) => void]
7
8function useLockedBody(initialLocked = false): ReturnType {
9  const [locked, setLocked] = useState(initialLocked)
10
11  // Do the side effect before render
12  useIsomorphicLayoutEffect(() => {
13    if (!locked) {
14      return
15    }
16
17    // Save initial body style
18    const originalOverflow = document.body.style.overflow
19    const originalPaddingRight = document.body.style.paddingRight
20
21    // Lock body scroll
22    document.body.style.overflow = 'hidden'
23
24    // Get the scrollBar width
25    const root = document.getElementById('___gatsby') // or root
26    const scrollBarWidth = root ? root.offsetWidth - root.scrollWidth : 0
27
28    // Avoid width reflow
29    if (scrollBarWidth) {
30      document.body.style.paddingRight = `${scrollBarWidth}px`
31    }
32
33    return () => {
34      document.body.style.overflow = originalOverflow
35
36      if (scrollBarWidth) {
37        document.body.style.paddingRight = originalPaddingRight
38      }
39    }
40  }, [locked])
41
42  // Update state if initialValue changes
43  useEffect(() => {
44    if (locked !== initialLocked) {
45      setLocked(initialLocked)
46    }
47    // eslint-disable-next-line react-hooks/exhaustive-deps
48  }, [initialLocked])
49
50  return [locked, setLocked]
51}
52
53export default useLockedBody

Usage

1import React, { CSSProperties, useState } from 'react'
2
3import { useLockedBody } from 'usehooks-ts'
4
5const fixedCenterStyle: CSSProperties = {
6  position: 'fixed',
7  top: '50%',
8  left: '50%',
9  transform: 'translate(-50%, -50%)',
10}
11
12const fakeScrollableStyle: CSSProperties = {
13  minHeight: '150vh',
14  background: 'linear-gradient(palegreen, palegoldenrod, palevioletred)',
15}
16
17// Example 1: useLockedBody as useState()
18export default function App() {
19  const [locked, setLocked] = useLockedBody()
20
21  const toggleLocked = () => {
22    setLocked(!locked)
23  }
24
25  return (
26    <div style={fakeScrollableStyle}>
27      <button style={fixedCenterStyle} onClick={toggleLocked}>
28        {locked ? 'unlock scroll' : 'lock scroll'}
29      </button>
30    </div>
31  )
32}
33
34// Example 2: useLockedBody with our custom state
35export function App2() {
36  const [locked, setLocked] = useState(false)
37
38  const toggleLocked = () => {
39    setLocked(!locked)
40  }
41
42  useLockedBody(locked)
43
44  return (
45    <div style={fakeScrollableStyle}>
46      <button style={fixedCenterStyle} onClick={toggleLocked}>
47        {locked ? 'unlock scroll' : 'lock scroll'}
48      </button>
49    </div>
50  )
51}

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Summary

useLockedBody()

The Hook

Usage