All Challengesbeginner

Read this React hook

The most common React pattern AI writes for managing component data.

typescript
import { useState, useEffect } from 'react'

function useWindowWidth() {
  const [width, setWidth] = useState(window.innerWidth)

  useEffect(() => {
    function handleResize() {
      setWidth(window.innerWidth)
    }
    window.addEventListener('resize', handleResize)
    return () => window.removeEventListener('resize', handleResize)
  }, [])

  return width
}

Question

What does the "return () =>" line inside useEffect do?

PreviousNext