Find second last element of linked list in node js

Js program for Find second last element of linked list. Here more information.

// Node JS program for
// Find the second last node of a linked list

// Node of Linked List
class LinkNode
{
	constructor(data)
	{
		// Set node value
		this.data = data;
		this.next = null;
	}
}
class SingleLL
{
	constructor()
	{
		this.head = null;
		this.tail = null;
	}
	// Add new node at the end of linked list
	insert(value)
	{
		// Create a new node
		var node = new LinkNode(value);
		if (this.head == null)
		{
			this.head = node;
		}
		else
		{
			this.tail.next = node;
		}
		this.tail = node;
	}
	// Display linked list element
	display()
	{
		if (this.head == null)
		{
			return;
		}
		var temp = this.head;
		// iterating linked list elements
		while (temp != null)
		{
			process.stdout.write(temp.data + " → ");
			// Visit to next node
			temp = temp.next;
		}
		process.stdout.write("null\n");
	}
	//Find the second last node of a linked list
	secondLast()
	{
		var node = this.head;
		if (node == null)
		{
			process.stdout.write("Empty linked list");
		}
		else if (node.next == null)
		{
			process.stdout.write("Only one node in this linked list");
		}
		else
		{
			// Find second last node
			while (node.next != null && node.next.next != null)
			{
				// Visit to second next node
				node = node.next.next;
			}
			console.log("Second last element is : " + node.data);
		}
	}
}

function main()
{
	var sll = new SingleLL();
	// Add linked list node
	sll.insert(6);
	sll.insert(3);
	sll.insert(2);
	sll.insert(7);
	sll.insert(1);
	sll.insert(9);
	console.log("Linked List");
	// 6 → 3 → 2 → 7 → 1 → 9 → null
	sll.display();
	sll.secondLast();
}
// Start program execution
main();

Output

Linked List
6 → 3 → 2 → 7 → 1 → 9 → null
Second last element is : 1