Getting Depth of Binary Tree

getTreeHeight.js

function Node(value = null, left = null, right = null) {
  return {
    value,
    left,
    right
  }
}

const isEdgeLeaf = node => !node.left && !node.right
const getHeight = (node, height = 0) => {
  if (isEdgeLeaf(node)) return height

  const lval = node.left != null ? getHeight(node.left, height + 1) : -1
  const rval = node.right != null ? getHeight(node.right, height + 1) : -1

  return Math.max(lval, rval)
}

const tree = Node(
  5,
  Node(
    3,
    Node(8, null, null),
    Node(7,
      Node(1, null, null),
      null)),
  Node(
    4,
    null,
    Node(6, null, null))
)

const height = getHeight(tree)
console.log(height) // 3