button started doing something

src/lib/components/preview.svelte

@@ -15,6 +15,14 @@
   let hidden: boolean = $derived(mobile ? $pane !== 'preview' : true);
 
   let output: Promise<string> = $derived(renderPreview(markdown, stylesheet));
+
+  async function performRender(event: MouseEvent) {
+    event.preventDefault();
+    const data = new FormData();
+    data.append('markdown', markdown);
+    data.append('stylesheet', stylesheet);
+    console.log(await fetch('/render', { method: 'POST', body: data }));
+  }
 </script>
 
 <main class:hidden class:mobile data-testid="preview-pane">
@@ -22,7 +30,7 @@
     <p>processing...</p>
   {:then result}
     <iframe title="résumé preview" srcdoc={result}></iframe>
-    <button>
+    <button type="submit" onclick={performRender}>
       <span>download</span>
       <iconify-icon icon="ion:download-outline" height="1.25em"></iconify-icon>
     </button>

src/routes/render/+server.ts

@@ -1,13 +1,11 @@
 import { error, json, type RequestEvent } from '@sveltejs/kit';
 
 export async function POST({ request }: RequestEvent) {
-  if (!(request.headers.get('Content-Type') ?? 'bad').includes('text/html')) {
-    error(400, 'request body not HTML');
-  }
-
   if (!request.body) {
     error(400, 'no body in request');
   }
 
+  console.log(request);
+
   return json({ msg: 'to be implemented' });
 }