From b8dc2f5b7d90264e1c8a41bdbed03e5f7f57b22e Mon Sep 17 00:00:00 2001
From: Eric Liu <ericyl.us@gmail.com>
Date: Fri, 22 Nov 2024 12:19:38 -0800
Subject: [PATCH] fix(tree-view): do not traverse original `nodes`

---
 src/TreeView/TreeView.svelte | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/src/TreeView/TreeView.svelte b/src/TreeView/TreeView.svelte
index 260ba14510..7dad10fdf3 100644
--- a/src/TreeView/TreeView.svelte
+++ b/src/TreeView/TreeView.svelte
@@ -207,24 +207,22 @@
   });
 
   /**
+   * Recursively flattens a tree of nodes into a single array
    * @param {Array<TreeNode & { nodes?: TreeNode[] }>} nodes
+   * @returns {Array<TreeNode>}
    */
   function traverse(nodes) {
-    let _nodes = [];
-
-    nodes.forEach((node) => {
-      _nodes.push(node);
-
-      if (Array.isArray(node.nodes)) {
-        _nodes = [...nodes, ...traverse(node.nodes)];
+    return nodes.reduce((acc, node) => {
+      acc.push(node);
+      if (Array.isArray(node.nodes) && node.nodes.length > 0) {
+        acc.push(...traverse(node.nodes));
       }
-    });
-
-    return _nodes;
+      return acc;
+    }, []);
   }
 
-  $: nodes = traverse(nodes);
-  $: nodeIds = nodes.map((node) => node.id);
+  $: flattenedNodes = traverse(nodes);
+  $: nodeIds = flattenedNodes.map((node) => node.id);
   $: activeNodeId.set(activeId);
   $: selectedNodeIds.set(selectedIds);
   $: expandedNodeIds.set(expandedIds);