LeetCode: linked-list-based queue, more performant than default JS's array-based one

simple-js-queue.js

function createQueue() {
    let head = undefined;
    let tail = head;

    function isEmpty() { return head === undefined; }
    function push(value) {
        const newElement = { next: undefined, value };
        if (!tail) {
            head = newElement;
            tail = newElement;
        } else {
            tail.next = newElement;
            tail = newElement;
        }
    }
    function pop() {
        const { value } = head;
        head = head.next;
        if (!head) tail = undefined;
        return value;
    }
    function peek() { return head.value; }
    return { isEmpty, push, pop, peek };
};