What will be the output of the following recursive function?

function countCharacter(str, char) {
  if (str.length === 0) {
    return 0;
  }
  let firstChar = str.charAt(0);
  let remainingStr = str.substr(1);
  if (firstChar === char) {
    return 1 + countCharacter(remainingStr, char);
  }
  return countCharacter(remainingStr, char);
}
console.log(countCharacter("Hello World", "o"));