What is the complexity of the algorithm?

Question

JavaScript

Help plz estimate the complexity of the algorithm (expands letters in words without changing the order of words):

const reverseWords = (str) => {
  const wordsArr = str.split(' ');
  const reversedArr = wordsArr.map((word) => {
    let newWord = '';
    for (let i = word.length - 1; i >= 0; i--) {
      newWord += word[i];
    }
    return newWord;
  });
  const reversedStr = reversedArr.join(' ');
  return reversedStr;
};

module.exports = reverseWords;
// O(n)?

According to my feelings, O (n) comes out.
I'm right? Or O(n*m)?

Answer 1

O(n), only 3 passes through the string: split, reverse, join.

Answer 2

In this implementation, most likely at least O(4n)
Split, reverse, join + concatenation (newWord+=)

Answer 3

I guess O(5n)