if ('serviceWorker' in navigator) {
    // Chrome, Firefox, Opera and Edge (16)

    /*
    *  scope (optional) default to the page root where it has been registered
    * */

    navigator.serviceWorker.register('/sw.js', {scope: './'}).then(function(registration) {
        console.log('Service worker registration succeeded:', registration);
    }).catch(function(error) {
        console.log('Service worker registration failed:', error);
    });
} else {
    // IE, Safari
    console.log('Service workers are not supported.');
}