Mumbling (7kyu) [JavaScript]

Chek kata on Codewars

Description:

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"
The parameter of accum is a string which includes only letters from a..z and A..Z.

Loop

function accum(s) {
  const result = []
  const lowerStr = s.toLowerCase()

  for(let i = 0; i < lowerStr.length; i++) {
    let str = lowerStr[i].toUpperCase()
    for(let j = 0; j < i; j++) {
      str += lowerStr[i]
    }
    result.push(str)
  }

  return result.join("-")
}

Map

function accum(s) {
  return [...s].map((char, index) => (char.toUpperCase() + char.toLowerCase().repeat(index))).join("-")
}

Reduce

function accum(s) {
  return [...s.toUpperCase()].reduce((acc, cur, index) => acc + "-" + cur + cur.toLowerCase().repeat(index))
}

---

function accum(s) {
  return [...s.toLowerCase()].reduce((acc, cur, index) => acc + (index != 0 ? "-" : "") + cur.toUpperCase() + cur.repeat(index), "")
}