es5-code-to-refactor.js

function upperCaseFirstLetter(word) {
  return word[0].toUpperCase() + word.slice(1);
}

function upperCaseWords(sentence) {
  var words = sentence.split(" ");
  for (var i = 0; i < words.length; i++) {
    words[i] = upperCaseFirstLetter(words[i]);
  }
  return words.join(" ");
}

console.log(upperCaseWords("code example to refactor"));