Limit text input 1-99

HTML

<input min="1" type="text" id="quantity" name="quantity" value="1" onKeyUp="numbersonly()">

<script>
function numbersonly() {
  var str = document.getElementById("quantity").value
  var num = 1
  var newstr = ""
  for (i = 0; i < str.length; i++) {
    for (ii = 1; ii < 10; ii++) {
      if (str.charAt(i).indexOf(num) > -1) {
        newstr += str.charAt(i)
      }
      num++
    }
    num = 1
  }
  if (newstr == "") {
    newstr = 1
  }
  if (parseInt(newstr) > 99) {
    newstr = 99
  }
  document.getElementById("quantity").value = newstr
}
</script>