Answers for "accum("abcd") -> "A-Bb-Ccc-Dddd" accum("RqaEzty") -> "R-Qq-Aaa-Eeee-Zzzzz-Tttttt-Yyyyyyy" accum("cwAt") -> "C-Ww-Aaa-Tttt""

accum("abcd") -> "A-Bb-Ccc-Dddd" accum("RqaEzty") -> "R-Qq-Aaa-Eeee-Zzzzz-Tttttt-Yyyyyyy" accum("cwAt") -> "C-Ww-Aaa-Tttt"

function accum(s) {
  var letters = s.split(''), words = [];

  for(var i = 0; i < letters.length; i++) {
    words.push(letters[i].toUpperCase() + Array(i + 1).join(letters[i].toLowerCase()));
  }

  return words.join('-');
}