Alternate case

[RazvanBugoi]

https://www.codewars.com/kata/57a62154cf1fa5b25200031e/train/javascript

[RazvanBugoi]

function alternateCase(s) {
  let str = ""

  for (let i=0; i<s.length; i++) {
    if (s[i] == s[i].toLowerCase()) {
      str += s[i].toUpperCase()
    } else {
      str += s[i].toLowerCase()
    }
  }

  return str
}