move fetch nodes by text id into its own function

re renders if theres a root list of nodes existing

public/js/text.js

@@ -8,15 +8,22 @@ document.addEventListener('DOMContentLoaded', () => {
             h1.textContent = text.name;
             document.getElementById('text-detail').appendChild(h1);
 
-            return fetch('/api/nodes/' + textId );
-        })
+            return fetchAndRenderNodes(textId);
+        });
+});
+
+function fetchAndRenderNodes(textId) {
+    return fetch('/api/nodes/' + textId)
         .then(res => res.json())
         .then(nodes => {
+            const existing = document.querySelector('#text-detail > ul');
+            if (existing) existing.remove();
+
             const tree = buildTree(nodes);
-            const ul = renderTree(tree);
+            const ul = renderTree(tree, textId);
             document.getElementById('text-detail').appendChild(ul);
         });
-});
+}
 
 function buildTree(nodes) {
     const map = {};