CTCI 3.5

sortStack.js

function sortStack(stack, sorted = false, inOrder = true) {
  if (sorted) return stack;

  const stackTwo = new Stack();
  let isSorted = true;

  while (stack !== null) {
    const top = stack.pop();

    if (stack.isEmpty()) {
      stackTwo.push(top);
      break;
    }

    const next = stack.pop();

    const topToStackTwo = () => {
      stackTwo.push(top);
      stack.push(next);
    };

    const nextToStackTwo = () => {
      stackTwo.push(next);
      stack.push(top);
    };

    if (inOrder) {
      if (top >= next) {
        topToStackTwo();
      } else {
        nextToStackTwo();
        isSorted = false;
      }
    } else {
      if (top >= next) {
        nextToStackTwo();
        isSorted = false;
      } else {
        topToStackTwo();
        isSorted = false;
      }
    }
  }

  return sortStack(stackTwo, isSorted, !inOrder);
}