1class Node {
2  constructor(val) {
3    this.val = val;
4    this.left = null;
5    this.right = null;
6  }
7}
8
9const one = new Node(1);
10const two = new Node(2);
11const three = new Node(3);
12const four = new Node(4);
13const five = new Node(5);
14const six = new Node(6);
15one.left = two;
16one.right = three;
17two.left = four;
18two.right = five;
19three.right = six;
20
21const inOrderDFS = (root, target) => {
22  if (!root) return null;
23  if (root.val === target) return true;
24  const leftSearch = inOrderDFS(root.left, target);
25  if (leftSearch) return leftSearch;
26  return inOrderDFS(root.right, target);
27};
28console.log(inOrderDFS(one, 4));
29console.log(inOrderDFS(one, 3));
30console.log(inOrderDFS(one, 7));
31console.log(inOrderDFS(one, 6));
32