How can i prevent from a function logging “undefined” in the console?

Question

I have a function that printing the defined string slowly.

function slowPrint(text, milliseconds) {
  var characterID = 0;
  var charactersArray = text.split('');
  var interval = setInterval(() => {
    while (characterID < text.length) {
      if (characterID < text.length) {
        process.stdout.write(charactersArray[characterID]);
        characterID += 1
      };
      if (characterID == text.length) {
        console.log(charactersArray[characterID])
        characterID = text.length + 2
      };
      if (characterID >= parseInt(text.length + 2)) {
        break;
      };
      break;
      clearInterval(interval);
    };
    if (characterID >= parseInt(text.length + 2)) {
      clearInterval(interval);
    };
  }, milliseconds);
};

slowPrint('test 12345', 200);

The code works without any mistakes, but running the function logging the console "undefined" when the printing the string is done.

Output:

test 12345undefined

Answer 1

That undefined output is caused by this line.

    console.log(charactersArray[characterID])

If you remove it you should get your expected result.

Answer 2

I have replaced

console.log(charactersArray[characterID])

with

process.stdout.write(charactersArray[characterID]);
process.stdout.write('\n');

and it worked perfectly!