test.js

function reverse (str) {
  return str.split('').reverse().join('')
}

function reverseSentence (str) {
  var splitString = str.split(' ')
  for (let i = 0; i < splitString.length; i++) {
    splitString[i] = reverse(splitString[i])
  }
  var reversed = splitString.join(' ')
  return reversed
}

function reverseWords (str) {
  var splitString = str.split(' ')
  var reversedArr = []
  for (let i = 0; i < splitString.length; i++) {
    reversedArr.unshift(splitString[i])
  }
  var reversed = reversedArr.join(' ')
  console.log(reversed)
  return reversed
}

function reverseWords2 (str) {
  return str.split(' ').reverse().join(' ')
}