tools-only Subscribe to Derived State
Subscribe to derived boolean state instead of continuous values to reduce re-render frequency.
Incorrect (re-renders on every pixel change):
function Sidebar() {
const width = useWindowWidth() // updates continuously
const isMobile = width < 768
return <nav className={isMobile ? 'mobile' : 'desktop'} />
}
Correct (re-renders only when boolean changes):
function Sidebar() {
const isMobile = useMediaQuery('(max-width: 767px)')
return <nav className={isMobile ? 'mobile' : 'desktop'} />
}