Understanding Queues in JavaScript: From Concept to Code

class Queue {
    constructor() {
        this.data = []; // A queue is constructed as an array
    }
    enqueue(element) { 
        // The push() method adds an element at the end
        this.data.push(element); 
    }
    dequeue() {
        if(this.isEmpty()) 
            return "Underflow"; // If the queue is empty
        // The shift() method removes an element from the start
        return this.data.shift(); 
    }
    isEmpty() {
        // The length property checks if the queue is empty
        return !this.data.length; 
    }
}

let queue = new Queue();
queue.enqueue(1); // 1 is added at the end of the queue
queue.enqueue(2); // 2 is now at the end, and 1 moves a step forward 
queue.enqueue(3); // 3 joins at the end, pushing 2 and 1 further up
console.log(queue); // {data: [1, 2, 3]}

let queue = new Queue();
queue.enqueue(1); // 1 is the first to join the queue
queue.enqueue(2); 
queue.enqueue(3);
queue.dequeue(); // 1 is removed as it was the first to join
console.log(queue); // {data: [2, 3]}