Recursive Staircase Problem in Javascript

function StairCase(n, step) {
  if (!step) {
    step = 1;
  }
  if (step > n) {
    return;
  }
  let str = "";
  for (var i = n; i > 0; i--) {
    if (i > step) {
      str += " ";
    } else {
      str += "*";
    }
  }
  console.log(str);
  StairCase(n, step + 1);
}

Usage

StairCase(6);