Sum of all right leaf nodes of binary tree in node js

Js program for Sum of all right leaf nodes of binary tree. Here mentioned other language solution.

/*
    Node JS program for
    Sum of all right leaves nodes in a binary tree
    Using recursion
*/
// Binary Tree node
class TreeNode
{
	constructor(data)
	{
		// Set node value
		this.data = data;
		this.left = null;
		this.right = null;
	}
}
class BinaryTree
{
	constructor()
	{
		this.root = null;
	}
	// Display pre order elements
	preorder(node)
	{
		if (node != null)
		{
			// Print node value
			process.stdout.write("  " + node.data);
			this.preorder(node.left);
			this.preorder(node.right);
		}
	}
	// Returns the Sum of all the right leaves in binary tree
	rightLeavesSum(node)
	{
		var sum = 0;
		if (node != null)
		{
			if (node.right != null && 
                node.right.left == null && 
                node.right.right == null)
			{
				// When get right leaf node
				sum = node.right.data;
			}
			// Recursively visit left and right subtree.
			// And find sum of right leaf nodes
			sum = sum + this.rightLeavesSum(node.left) +
              this.rightLeavesSum(node.right);
		}
		return sum;
	}
}

function main()
{
	// New binary tree
	var tree = new BinaryTree();
	/*
	    Constructor binary tree
	    -----------------------
	          6
	         / \ 
	        /   \                             
	       /     \    
	      2       3     
	     / \       \               
	    8   10      1
	       /  \    / \
	      6   -2  4   5
	*/
	// Add tree node
	tree.root = new TreeNode(6);
	tree.root.left = new TreeNode(2);
	tree.root.left.left = new TreeNode(8);
	tree.root.left.right = new TreeNode(10);
	tree.root.left.right.right = new TreeNode(-2);
	tree.root.left.right.left = new TreeNode(6);
	tree.root.right = new TreeNode(3);
	tree.root.right.right = new TreeNode(1);
	tree.root.right.right.left = new TreeNode(4);
	tree.root.right.right.right = new TreeNode(5);
	process.stdout.write("\n Tree Nodes : ");
	tree.preorder(tree.root);
	// Find right leaf sum
	var sum = tree.rightLeavesSum(tree.root);
	// Display result
	process.stdout.write("\n Right leaves nodes sum : " + sum);
}
// Start program execution
main();

Output

 Tree Nodes :   6  2  8  10  6  -2  3  1  4  5
 Right leaves nodes sum : 3