useRouter/withRouter receive undefined on query in first render

I found something:

isReady: boolean – Whether the router fields are updated client-side and ready for use. Should only be used inside of useEffect methods and not for conditionally rendering on the server.
https://nextjs.org/docs/api-reference/next/router#router-object

And the code would be like:

const router = useRouter();
useEffect(()=>{
    if(!router.isReady) return;

    // codes using router.query

}, [router.isReady]);