提供JavaScript版本的《二叉搜索树中的插入操作》

problems/0701.二叉搜索树中的插入操作.md

@@ -286,6 +286,39 @@ func insertIntoBST(root *TreeNode, val int) *TreeNode {
 }
 ```
 
+JavaScript版本
+
+> 有返回值的递归写法
+
+```javascript
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {number} val
+ * @return {TreeNode}
+ */
+var insertIntoBST = function (root, val) {
+    const setInOrder = (root, val) => {
+        if (root === null) {
+            let node = new TreeNode(val);
+            return node;
+        }
+        if (root.val > val)
+            root.left = setInOrder(root.left, val);
+        else if (root.val < val)
+            root.right = setInOrder(root.right, val);
+        return root;
+    }
+    return setInOrder(root, val);
+};
+```