Get diameter of a binary tree with javascript recursive impelemntation

GetDiameter.js

function getDiameterAndHeight(tree) {
	if (tree === null) return { diameter: 0, height: 0 }
	
	const leftTreeInfo = getDiameterAndHeight(tree.left)
	const rightTreeInfo = getDiameterAndHeight(tree.right)
	
	const diameterFromRoot = leftTreeInfo.height + rightTreeInfo.height
	const longestDiameterSoFar = Math.max(leftTreeInfo.diameter, rightTreeInfo.diameter)
	const diameter = Math.max(diameterFromRoot, longestDiameterSoFar)
	const height =  Math.max(leftTreeInfo.height, rightTreeInfo.height) + 1
	return { diameter, height }
}

function binaryTreeDiameter(tree) {
  // Write your code here.
  return getDiameterAndHeight(tree).diameter;
}