index.html

<!DOCTYPE html>
<html>
    <head>
        <title>Home page</title>
        <script async src="https://www.googletagmanager.com/gtag/js?id=G-B00VND1H2L"></script>
        <script>
        window.dataLayer = window.dataLayer || [];
        function gtag(){dataLayer.push(arguments);}
        gtag('js', new Date());

        gtag('config', 'G-B00VND1H2L', { 'debug_mode':true });
        </script>
    </head>
    <body>
        <script>
            document.addEventListener("DOMContentLoaded", () => {
                const start = new Date().getTime();
                window.addEventListener("beforeunload", () => {
                    const end = new Date().getTime();
                    const totalTime = (end - start) / 1000
                
                    console.log(totalTime)
                });
            });
        </script>
        <p>Home Page</p>
        <a href="https://aurelienmozoo.github.io/landing-page">Go to landing page</a>
    </body>
</html>