electron/spec/fixtures/pages/service-worker/badge-index.html

<script>
  const ipcRenderer = require('electron').ipcRenderer;
  let search = (new URL(document.location)).search;

  async function testIt() {
    if (search === '?clearBadge') {
      try {
        await navigator.setAppBadge(42);
        ipcRenderer.send('setAppBadge','SUCCESS setting app badge');
      } catch (error) {
        ipcRenderer.send('error', `${error.message}\n${error.stack}`);
      }
    }
    navigator.serviceWorker.register('service-worker-badge.js', {scope: './'}).then(function() {
      if (navigator.serviceWorker.controller) {
        var xhr = new XMLHttpRequest();
        xhr.open('GET', 'http://dummy/echo'+search);
        xhr.setRequestHeader('X-Mock-Response', 'yes');
        xhr.addEventListener('load', function() {
          ipcRenderer.send('response', xhr.responseText);
        });
        xhr.send();
      } else {
        ipcRenderer.send('reload');
      }
    }).catch(function(error) {
      ipcRenderer.send('error', `${error.message}\n${error.stack}`);
    })
  }
  testIt();
</script>