How to convert bottom-up recursive algorithm to iterative stack in JavaScript

Answer 1

Let's start with just the is:

function create(i) {
  console.log(i)

  if (i == 3) return

  return new Klass(i, create(i+1), create(i+1))
}

function Klass(i, l, r) {
  this.i = i
  this.l = l
  this.r = r
}

console.log(JSON.stringify(create(0)))

console.log('\nStack version:')

let stack = [0];

while (stack.length){
  let i = stack.pop();

  console.log(i);

  if (i < 3)
    stack.push(i + 1, i + 1);
}

There are so many ways we could use the iteratively generated order of is; from pushing them all to an array, then following the trail of assignments backwards; to using the i to create a new Klass and passing it by reference, essentially turning the process into top-down.