Detect leaf nodes of threaded BST in node js

Js program for Detect leaf nodes in threaded BST. Here mentioned other language solution.

// Node JS program for
// Print leaf node in Threaded BST
class TreeNode
{
	constructor(data, left, right)
	{
		this.data = data;
		this.left = left;
		this.right = right;
	}
}
class BinarySearchTree
{
	constructor()
	{
		this.root = null;
	}
	// Added node in Threaded BST
	addNode(node, x, y, data)
	{
		if (node != null)
		{
			if (node.data >= data)
			{
				if (node.left == x)
				{
					node.left = new TreeNode(data, x, node);
				}
				else
				{
					node.left = this.addNode(node.left, x, node, data);
				}
			}
			else if (node.data < data)
			{
				if (node.right == y)
				{
					node.right = new TreeNode(data, node, y);
				}
				else
				{
					node.right = this.addNode(node.right, node, y, data);
				}
			}
			return node;
		}
		else
		{
			return new TreeNode(data, x, y);
		}
	}
	// Adding a new node in binary search tree
	add(data)
	{
		this.root = this.addNode(this.root, null, null, data);
	}
	// Print all leaf node in Threaded BST
	leafNode(node, x, y)
	{
		if (node != null)
		{
			if (node.left == x && node.right == y)
			{
				// This is a leaf node Then print
				process.stdout.write("  " + node.data);
				return;
			}
			if (node.left != x)
			{
				// Visit left child
				this.leafNode(node.left, x, node);
			}
			if (node.right != y)
			{
				// Visit right child
				this.leafNode(node.right, node, y);
			}
		}
	}
}

function main()
{
	var tree = new BinarySearchTree();
	// Add nodes in binary search tree
	/*
	            5
	           / \
	          /   \
	         /     \
	        3       9
	       / \     / \
	      1   4   8   11
	     / \     /      \
	   -3   2   7        12
	        
	*/
	tree.add(5);
	tree.add(3);
	tree.add(9);
	tree.add(1);
	tree.add(4);
	tree.add(8);
	tree.add(11);
	tree.add(-3);
	tree.add(2);
	tree.add(7);
	tree.add(12);
	// Test
	tree.leafNode(tree.root, null, null);
}
// Start program execution
main();

Output

  -3  2  4  7  12