ink.rel = &quot;prefetch&quot;;
      link.href = testURI(&quot;resource&quot;, &quot;prefetch&quot;, key);
      document.getElementsByTagName(&quot;head&quot;)[0].appendChild(link);
      return key;
    }

read: async (key) =&gt; {
      let link = document.createElement(&quot;link&quot;);
      link.rel = &quot;prefetch&quot;;
      link.href = testURI(&quot;resource&quot;, &quot;prefetch&quot;, key);
      document.getElementsByTagName(&quot;head&quot;)[0].appendChild(link);
      await sleepMs(500);
 