Stacks Development Tutorials, Guides & Insights

A queue is a FIFO (First In, First Out) data structure. The first element added is the first one to be removed.

class Queue {
    constructor() {
        this.items = [];
    }

    enqueue(element) {
        this.items.push(element);
    }

    dequeue() {
        if (this.isEmpty()) return "Underflow";
        return this.items.shift();
    }

    front() {
        if (this.isEmpty()) return "No elements in Queue";
        return this.items[0];
    }

    isEmpty() {
        return this.items.length === 0;
    }

    printQueue() {
        let queueString = "";
        for (let i = 0; i < this.items.length; i++) {
            queueString += this.items[i] + " ";
        }
        return queueString;
    }
}

let queue = new Queue();
queue.enqueue(10);
queue.enqueue(20);
queue.enqueue(30);
console.log(queue.printQueue()); // Output: 10 20 30
queue.dequeue();
console.log(queue.printQueue()); // Output: 20 30