added initial istio BLAHAJ code

apps/reef/public/app.js

@@ -0,0 +1,44 @@
+const endpoints = [
+	{ path: '/blahaj', title: 'bubbles greeter (blahaj)' },
+	{ path: '/kelp', title: 'kelp' },
+	{ path: '/coral', title: 'coral' },
+	{ path: '/bubbles', title: 'bubbles' },
+];
+
+const cards = document.querySelector('#cards');
+
+function cardDOM({ title, ok, data, error }) {
+	const el = document.createElement('article');
+	el.className = `card ${ok ? 'ok' : 'err'}`;
+
+	const h2 = document.createElement('h2');
+	h2.textContent = title;
+	el.appendChild(h2);
+
+	const pre = document.createElement('pre');
+	pre.textContent = ok ? JSON.stringify(data, null, 2) : String(error || 'error');
+	el.appendChild(pre);
+
+	return el;
+}
+
+async function fetchOne(path) {
+	const r = await fetch(path, { headers: { 'accept': 'application/json' } });
+	if (!r.ok) throw new Error(`${path} -> ${r.status}`);
+	return r.json();
+}
+
+async function refresh() {
+	cards.textContent = ''; // clear
+	for (const ep of endpoints) {
+		try {
+			const data = await fetchOne(ep.path);
+			cards.appendChild(cardDOM({ title: ep.title, ok: true, data }));
+		} catch (err) {
+			cards.appendChild(cardDOM({ title: ep.title, ok: false, error: err.message }));
+		}
+	}
+}
+
+document.querySelector('#refresh').addEventListener('click', () => refresh());
+refresh();