effects-cleanup-resize.js

import React, { useState, useEffect } from 'react'

function Example() {
  const [width, setWidth] = useState(...)

  useEffect(() => {
    function handleResize(event) {
      // Calculate window width...
      setWidth(...)
    }

    window.addEventListener('resize', handleResize)
    
    // Specify how to clean up after this effect:
    return () => {
      window.removeEventListener('resize', handleResize)
    }
  })

  return (
    <>
      ...
    </>
  )
}