minimal implementation for a queue backed by a singly linked list

LinkedQueue.js

class LinkedQueue {
    constructor() {
        this._newest = null;
        this._oldest = null;
        this._size = 0;
    }

    enqueue(item) {
        if (this._size === 0) {
            this._newest = {value: item, next: null};
            this._oldest = this._newest;
        } else {
            const temp = {value: item, next: null};
            this._newest.next = temp;
            this._newest = temp;
        }
        this._size++;
    }

    dequeue() {
        const oldest = this._oldest;
        const result = oldest.value;
        oldest.value = null;
        this._oldest = oldest.next;
        this._size--;
        return result;
    }
}