Add ESP32 WiFi interface (#11209)

data/www/marlin.js

@@ -0,0 +1,24 @@
+document.addEventListener('DOMContentLoaded', () => {
+  const ws = new WebSocket(`ws://${location.host}/ws`);
+
+  ws.onmessage = (e) => {
+    if (typeof e.data === 'string') {
+      let node = document.createElement('li');
+      let text = document.createTextNode(e.data);
+      node.appendChild(text);
+      document.getElementById('serial-output').appendChild(node);
+    }
+  };
+
+  document.getElementById('serial-command-form').addEventListener('submit', (e) => {
+    e.preventDefault();
+
+    let value = document.getElementById('serial-command').value.trim();
+
+    if (!value) return;
+
+    ws.send(`${value}\n`);
+
+    document.getElementById('serial-command').value = '';
+  });
+});