Queue

queue.js

class Node {
    constructor(value) {
        this.value = value;
        this.next = null;
    }
}

class Queue {
    constructor() {
        this.size = 0;
        this.first = null;
        this.last = null;
    }

    enqueue(value) {
        const newNode = new Node(value);

        if (!this.first) {
            this.first = newNode;
            this.last = this.first;
        } else {
            this.last.next = newNode;
            this.last = newNode;
        }

        return ++this.size;
    }

    dequeue() {
        if (!this.first) return;

        const temp = this.first;

        if (this.first === this.last) {
            this.last = null;
        }

        this.first = temp.next;
        this.size--;

        return temp.value;
    }
}

const queue = new Queue();

queue.enqueue(1);
queue.enqueue(2);
queue.enqueue(4);

queue.dequeue();