Triple order traversal of a binary tree in typescript

Ts program for Triple order traversal of a binary tree. Here mentioned other language solution.

/*
    TypeScript program for
    Triple order traversal of a binary tree
*/
// Binary Tree node
class TreeNode
{
	public data: number;
	public left: TreeNode;
	public right: TreeNode;
	constructor(data: number)
	{
		// Set node value
		this.data = data;
		this.left = null;
		this.right = null;
	}
}
class BinaryTree
{
	public root: TreeNode;
	constructor()
	{
		// Set initial tree root
		this.root = null;
	}
	public tripleOrder(node: TreeNode)
	{
		if (node != null)
		{
			// Print preorder node
			console.log(" " + node.data);
			// Visit left subtree
			this.tripleOrder(node.left);
			// Print inorder node
			console.log(" " + node.data);
			// Visit right subtree
			this.tripleOrder(node.right);
			// Print postorder node
			console.log(" " + node.data);
		}
	}
	public static main()
	{
		// Create new binary trees
		var tree = new BinaryTree();
		/*
		         4    
		        / \                         
		       /   \    
		     -4     7    
		     / \     \               
		    2   3     1
		       / \   / 
		      6   8 5
		     /       
		    9          
		  ----------------------
		  Constructing binary tree
		        
		*/
		tree.root = new TreeNode(4);
		tree.root.left = new TreeNode(-4);
		tree.root.left.right = new TreeNode(3);
		tree.root.left.right.left = new TreeNode(6);
		tree.root.left.right.left.left = new TreeNode(9);
		tree.root.left.right.right = new TreeNode(8);
		tree.root.left.left = new TreeNode(2);
		tree.root.right = new TreeNode(7);
		tree.root.right.right = new TreeNode(1);
		tree.root.right.right.left = new TreeNode(5);
		// Print triple order
		// ----------------------------------
		// 4 -4 2 2 2 -4 3 6 9 9 9 6 6 3 8 8 ..
		// 8 3 -4 4 7 7 1 5 5 5 1 1 7 4
		tree.tripleOrder(tree.root);
	}
}
BinaryTree.main();
/*
 file : code.ts
 tsc --target es6 code.ts
 node code.js
 */

Output

 4
 -4
 2
 2
 2
 -4
 3
 6
 9
 9
 9
 6
 6
 3
 8
 8
 8
 3
 -4
 4
 7
 7
 1
 5
 5
 5
 1
 1
 7
 4