another-guy

function createStack() {
  const empty = { next: undefined, value: undefined! };
  let top = empty;
  function isEmpty() { return top === empty; }
  function push(v) { top = { next: top, value: v }; }
  function pop() {
      if (!top.next) throw new Error('Can not pop from empty');
      const { value } = top;
      top = top.next;
      return value;

another-guy

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;

another-guy

// TS
function test<T extends unknown>(actual: T, expected: T, text?: string): void {
  function difference<D>(a: Set<D>, b: Set<D>) {
    const arr: D[] = [];
    a.forEach(d => arr.push(d));
    return new Set<D>(arr.filter(x => !b.has(x)));
  }
  function same<S extends unknown>(o1: S, o2: S): boolean {
    const t1 = typeof o1;
    const t2 = typeof o2;