Maximum Depth of Binary Tree LeetCode solution in JavaScript

1
var maxDepth = function (root) {
2
  if (root == null) return 0;
3

4
  let leftDepth = maxDepth(root.left);
5
  let rightDepth = maxDepth(root.right);
6

7
  let ans = Math.max(leftDepth, rightDepth) + 1;
8

9
  return ans;
10
};