setTimeout Javascript 'Timer'

Question

let doit = (from, to) => {
  let a = setTimeout(doit, 500, ++from);
  console.table(from);
  if (from === to) {
    clearTimeout(a)
  }
};

 doit(6, 13);

Write a printNumbers(from, to) function that prints a number every second, starting from from and ending with to . Can you describe me why this timer is not stopping? Can you answer with comments please.