Convert singly linked list to circular list in typescript

Ts program for Convert singly linked list to circular list. Here problem description and explanation.

// TypeScript program for
// Convert singly linked list into circular list

// Define class of linked list Node
class LinkNode
{
	public data: number;
	public next: LinkNode;
	constructor(data: number)
	{
		this.data = data;
		this.next = null;
	}
}
class LinkedList
{
	public head: LinkNode;
	// Class constructor
	constructor()
	{
		this.head = null;
	}
	// Check circular linked list or not
	// Note that this function is not capable to detect loop
	public boolean isCircular()
	{
		if (this.head == null)
		{
			// Case when linked list is empty
			return false;
		}
		else
		{
			var temp = this.head;
			while (temp != null)
			{
				// Visit to next node
				temp = temp.next;
				if (temp == this.head)
				{
					// When detecting circular node
					return true;
				}
			}
			// When not circular linked list
			return false;
		}
	}
	// Display node element of linked list
	public display()
	{
		if (this.head == null)
		{
			console.log("Empty Linked List");
		}
		else
		{
			console.log("Linked List Element :");
			var temp = this.head;
			// Iterate linked list
			while (temp != null)
			{
				// Display node
				console.log("  " + temp.data);
				// Visit to next node
				temp = temp.next;
				if (temp == this.head)
				{
					// Stop iteration
					return;
				}
			}
			console.log();
		}
	}
	// Coverted circular Linked list
	public makeCircular()
	{
		if (this.head == null)
		{
			console.log("Empty Linked List");
		}
		else
		{
			var temp = this.head;
			// Find last node
			while (temp.next != null)
			{
				temp = temp.next;
				if (temp == this.head)
				{
					// Already circular Linked list
					return;
				}
			}
			// Connect last node to first node
			temp.next = this.head;
		}
	}
	public static main(args: string[])
	{
		var ll = new LinkedList();
		// Insert element of linked list
		ll.head = new LinkNode(1);
		ll.head.next = new LinkNode(2);
		ll.head.next.next = new LinkNode(3);
		ll.head.next.next.next = new LinkNode(4);
		ll.head.next.next.next.next = new LinkNode(5);
		ll.head.next.next.next.next.next = new LinkNode(6);
		ll.head.next.next.next.next.next.next = new LinkNode(7);
		ll.display();
		if (ll.isCircular())
		{
			console.log("Circular Yes");
		}
		else
		{
			console.log("Circular No");
		}
		console.log("After Convert");
		ll.makeCircular();
		if (ll.isCircular())
		{
			console.log("Circular Yes");
		}
		else
		{
			console.log("Circular No");
		}
	}
}
LinkedList.main([]);
/*
 file : code.ts
 tsc --target es6 code.ts
 node code.js
 */

Output

Linked List Element :
  1
  2
  3
  4
  5
  6
  7

Circular No
After Convert
Circular Yes