From 30bd0faecbedad6ba29bd062ae7acef369d25071 Mon Sep 17 00:00:00 2001
From: wangdaodao <hi@wangdaodao.com>
Date: Tue, 20 Aug 2024 15:38:41 +0800
Subject: [PATCH] fix: Tree Draggable does not work on Firefox

---
 packages/tree/src/tree.vue | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/tree/src/tree.vue b/packages/tree/src/tree.vue
index 5b1c1b4c4ec..e1d147038a5 100644
--- a/packages/tree/src/tree.vue
+++ b/packages/tree/src/tree.vue
@@ -447,7 +447,9 @@
       this.$on('tree-node-drag-end', (event) => {
         const { draggingNode, dropType, dropNode } = dragState;
         event.preventDefault();
-        event.dataTransfer.dropEffect = 'move';
+        if (event.dataTransfer) {
+          event.dataTransfer.dropEffect = 'move';
+        }
 
         if (draggingNode && dropNode) {
           const draggingNodeCopy = { data: draggingNode.node.data };