Measure the Core Web Vitals without a bundler

module.html

<!-- Load `web-vitals` using a module script. -->
<script type="module">
  import {getCLS, getFID, getLCP} from 'https://unpkg.com/web-vitals@0.2.1/dist/web-vitals.es5.min.js?module';

  getCLS(console.log);
  getFID(console.log);
  getLCP(console.log);
</script>

script.html

<!-- Load `web-vitals` using a classic script that sets the global `webVitals` object. -->
<script defer src="https://unpkg.com/web-vitals@0.2.1/dist/web-vitals.es5.umd.min.js"></script>
<script>
addEventListener('DOMContentLoaded', function() {
  webVitals.getCLS(console.log);
  webVitals.getFID(console.log);
  webVitals.getLCP(console.log);
});
</script>