Mobile offline

index(html)1.js

      if ( 'serviceWorker' in navigator ) {
        navigator.serviceWorker.register('sw.js').then(function(registration) {
          // Registration was successful
          console.log('ServiceWorker registration successful with scope: ', registration.scope);
        }).catch(function(err) {
          // registration failed :(
          console.log('ServiceWorker registration failed: ', err);
        });