diff --git a/problems/二叉树理论基础.md b/problems/二叉树理论基础.md
index abeeae67..edd1fed4 100644
--- a/problems/二叉树理论基础.md
+++ b/problems/二叉树理论基础.md
@@ -223,6 +223,14 @@ type TreeNode struct {
 }
 ```
 
+JavaScript：
+```
+function TreeNode(val, left, right) {
+    this.val = (val===undefined ? 0 : val)
+    this.left = (left===undefined ? null : left)
+    this.right = (right===undefined ? null : right)
+}
+```
 
 
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