index.ssr.html

<div class="fetch-json-module">
  json-module:
  <pre></pre>
  <code></code>
</div>
<div class="fetch-json-fs">
  json-fs:
  <pre></pre>
  <code></code>
</div>

<script type="module">
  const startModule = Date.now()
  text('.fetch-json-module pre', await (await fetch('/json-module')).text())
  text('.fetch-json-module code', Date.now() - startModule)

  const startFs = Date.now()
  text('.fetch-json-fs pre', await (await fetch('/json-fs')).text())
  text('.fetch-json-fs code', Date.now() - startFs)
  function text(sel, text) {
    document.querySelector(sel).textContent = text
  }
</script>