Get case / type of a string's character by position in Javascript

char_type_js.txt

<script>
function charType(chr, pos) {
            
  pos = (pos === undefined) ? 0 : parseInt(pos);
            
  var ret = "O";
  var code = chr.charCodeAt(pos);

  if (code >= "A".charCodeAt(0) && code <= "Z".charCodeAt(0)) {
    return "U";
  } else if (code >= "a".charCodeAt(0) && code <= "z".charCodeAt(0)) {
    return "L";
  } else if (code >= "0".charCodeAt(0) && code <= "9".charCodeAt(0)) {
    return "N";
  }
        
  return '';
}

//Usage - string & position (0 index)
var str = "Hello World!";
var pos = 0;

switch (charType(str,pos)) {
  case "U":
    document.write("Character " + str[pos] + " is upper case");
    break;
  case "L":
    document.write("Character  " + str[pos] + " is lower case");
    break;
  case "N":
    document.write("Character  " + str[pos] + " is a number");
    break;
  default:
    document.write("Character  " + str[pos] + " is not a character or a number");
}
</script>