Example of Nextjs Splash screen _app.js

_app.js

function MyApp({ Component, pageProps }) {
    // Hide splash screen shen we are server side 
   useEffect(() => {
        if (typeof window !== 'undefined') {
                const loader = document.getElementById('globalLoader');
            if (loader)
                loader.style.display = 'none';
        }
    }, []);
  
    return <Component {...pageProps} />
}

export default MyApp