pwa/service-workers/index.html

<html lang="en">
    <head>
        <title>Example one flexbox</title>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width,initial-scale=1">
        <link rel="stylesheet" href="app.css">
    </head>
    <body>
        <main>
            <section id="container">
                <p>Hello world!</p>
            </section>
        </main>
        <script src="app.js"></script>
        <script>
            if(navigator.serviceWorker) {
                window.addEventListener('load', () => {
                    navigator.serviceWorker.register('sw.js').then((reg) => {
                        console.log('registration ok');
                    }).catch((e) => {
                        console.log('registration fails', e);
                    });
                });
            }
        </script>
    </body>
</html>