title: Why am I seeing "Error - Only secure origins are allowed" for my service worker?
body: <p>When I try to add a service worker on my progressive web app page, why does the browser console show the following error?</p>
  
  <pre><code>ERROR "Uncaught (in promise) DOMException: Only secure origins are allowed
  </code></pre>
  
  <p>JS Code:</p>
  
  <pre><code>(function () {
      'use strict';
  
      // TODO add service worker code here
      if ('serviceWorker' in navigator) {
          navigator.serviceWorker
              .register('service-worker.js')
              .then(function () {
                  console.log('Service Worker Registered');
              });
      }
  })();
  </code></pre>