support sorting stats table

stats/index.php

@@ -31,6 +31,27 @@ include __DIR__."/../header.php";
 		</table>
 	</div>
 	<hr>
-	<p>Available in <a href="/stats.json">JSON format</a>.</p>
+	<p>also available as <a href="/stats.json">json</a>.</p>
+
+	<script>
+		// sort stats page
+		const getCellValue = (tr, idx) => tr.children[idx].innerText || tr.children[idx].textContent;
+
+		const comparer = (idx, asc) => (a, b) => ((v1, v2) =>
+			v1 !== '' && v2 !== '' && !isNaN(v1) && !isNaN(v2) ? v1 - v2 : v1.toString().localeCompare(v2)
+			)(getCellValue(asc ? b : a, idx), getCellValue(asc ? a : b, idx));
+
+		// do the work...
+		document.querySelectorAll('th').forEach(function(th) {
+		  th.addEventListener('click', (() => {
+			const table = th.closest('table').querySelector("tbody");
+			Array.from(table.querySelectorAll('tr'))
+				.sort(comparer(Array.from(th.parentNode.children).indexOf(th), this.asc = !this.asc))
+				.forEach(tr => table.appendChild(tr) );
+		  }));
+		  th.style.cursor = 'pointer';
+		});
+	</script>
 
 <?php include __DIR__."/../footer.php"; ?>
+