CODE EXAMPLE FOR JAVASCRIPT

register a service worker

<script>
  if ('serviceWorker' in navigator) {
  window.addEventListener('load', function() {
  navigator.serviceWorker.register('service-worker.js').then(function(registration) {
  // Registration was successful
  console.log('Registered!');
  }, function(err) {
  // registration failed :(
  console.log('ServiceWorker registration failed: ', err);
  }).catch(function(err) {
  console.log(err);
  });
  });
  } else {
  console.log('service worker is not supported');
  }
  </script>