tree traversal recursion in javascript

   
    class Node {
       constructor(value){
       this.left = null;
       this.right = null;
       this.value = value;
      }
     }

    class BinarySearchTree {
         constructor(){
         this.root = null;
     }
    insert(value){
        const newNode = new Node(value);
    if (this.root === null) {
        this.root = newNode;
    } else {
        let currentNode = this.root;
        while(true){
        if(value < currentNode.value){
          //Left
          if(!currentNode.left){
            currentNode.left = newNode;
            return this;
          }
          currentNode = currentNode.left;
        } else {
          //Right
          if(!currentNode.right){
            currentNode.right = newNode;
            return this;
          } 
          currentNode = currentNode.right;
          }
         }
        }
       }  
      }

     const tree = new BinarySearchTree();
     tree.insert(9)
     tree.insert(4)
     tree.insert(6)
     tree.insert(20)
     tree.insert(170)
     tree.insert(15)
     tree.insert(1)
     JSON.stringify(traverse(tree.root))

    //     9
   //  4     20
   //1  6  15  170

  function traverse(node) {
      const tree = { value: node.value };
      tree.left=node.left
       if(node.left===null) {
            return  null
      }else{
           traverse(node.left);
      }     
      tree.right=node.right
          if(node.right===null) {
                 return null
          }else{
                 traverse(node.right);
            }
       }