$( document ).ready(function () {

    if ('serviceWorker' in navigator) {
        navigator.serviceWorker
            .register('/sw.js')
            .then(function(reg) {
                if(reg.installing) {
                    console.log('Service worker installing');
                } else if(reg.waiting) {
                    console.log('Service worker installed');
                } else if(reg.active) {
                    console.log('Service worker active');
                }
            }).catch(function(error) {
                console.log('Registration failed with ' + error);
            });
    }

});