Mumbling

This time no story, no theory. The examples below show you how to write function

accum:

Examples:

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

Solution:

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('-');
}