DSA-with-Javascript/A8 Stack and Queues/queues-linked-list.js at master · yashkathe/DSA-with-Javascript · GitHub

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

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

    enqueue(val) {

        let newNode = new Node(val);

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

        return ++this.size;
    }

    dequeue() {

        if(!this.first) return null;

        let temp = this.first;

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

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

    }

}

const q = new Queue();

console.log(q.enqueue(1));
console.log(q.enqueue(2));
console.log(q.enqueue(3));

console.log(q.dequeue());

console.log(q);