implement queue using linked list in node js

Js program for implement queue using linked list. Here problem description and other solutions.

/*
  Node JS Program for
  Implement queue using linked list
*/
// Create Q node
class QNode
{
	constructor(value)
	{
		this.data = value;
		this.next = null;
	}
}
class MyQueue
{
	constructor()
	{
		this.head = null;
		this.tail = null;
		this.count = 0;
	}
	size()
	{
		return this.count;
	}
	isEmpty()
	{
		return this.count == 0;
	}
	// Add new node of queue
	enqueue(value)
	{
		// Create a new node
		var node = new QNode(value);
		if (this.head == null)
		{
			// Add first element into queue
			this.head = node;
		}
		else
		{
			// Add node at the end using tail 
			this.tail.next = node;
		}
		this.count++;
		this.tail = node;
	}
	// Delete a element into queue
	dequeue()
	{
		if (this.head == null)
		{
			console.log("Empty Queue");
			return -1;
		}
		// Pointer variable which are storing 
		// the address of deleted node
		var temp = this.head;
		// Visit next node 
		this.head = this.head.next;
		this.count--;
		if (this.head == null)
		{
			// When deleting a last node of linked list
			this.tail = null;
		}
		return temp.data;
	}
	// Get front node
	peek()
	{
		if (this.head == null)
		{
			console.log("Empty Queue");
			return -1;
		}
		return this.head.data;
	}
}

function main()
{
	var task = new MyQueue();
	// Initially number of element
	console.log("isEmpty : " + task.isEmpty());
	// Add element into queue
	task.enqueue(10);
	task.enqueue(20);
	task.enqueue(30);
	task.enqueue(40);
	task.enqueue(50);
	// Test other function
	console.log("size : " + task.size());
	console.log("peek : " + task.peek());
	console.log("dequeue : " + task.dequeue());
	console.log("size : " + task.size());
	console.log("peek : " + task.peek());
	console.log("isEmpty : " + task.isEmpty());
}
// Start program execution
main();

Output

isEmpty : true
size : 5
peek : 10
dequeue : 10
size : 4
peek : 20
isEmpty : false


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