tree traversal recursion in javascript

1   
2    class Node {
3       constructor(value){
4       this.left = null;
5       this.right = null;
6       this.value = value;
7      }
8     }
9
10    class BinarySearchTree {
11         constructor(){
12         this.root = null;
13     }
14    insert(value){
15        const newNode = new Node(value);
16    if (this.root === null) {
17        this.root = newNode;
18    } else {
19        let currentNode = this.root;
20        while(true){
21        if(value < currentNode.value){
22          //Left
23          if(!currentNode.left){
24            currentNode.left = newNode;
25            return this;
26          }
27          currentNode = currentNode.left;
28        } else {
29          //Right
30          if(!currentNode.right){
31            currentNode.right = newNode;
32            return this;
33          } 
34          currentNode = currentNode.right;
35          }
36         }
37        }
38       }  
39      }
40
41     const tree = new BinarySearchTree();
42     tree.insert(9)
43     tree.insert(4)
44     tree.insert(6)
45     tree.insert(20)
46     tree.insert(170)
47     tree.insert(15)
48     tree.insert(1)
49     JSON.stringify(traverse(tree.root))
50
51    //     9
52   //  4     20
53   //1  6  15  170
54
55  function traverse(node) {
56      const tree = { value: node.value };
57      tree.left=node.left
58       if(node.left===null) {
59            return  null
60      }else{
61           traverse(node.left);
62      }     
63      tree.right=node.right
64          if(node.right===null) {
65                 return null
66          }else{
67                 traverse(node.right);
68            }
69       }