Generate two alphabet continous sequences till `ZZ`

generate.js

let startCharCode = 64

const letters = [
  'A', 'B', 'C', 'D', 'E', 'F',
  'G', 'H', 'I', 'J', 'K', 'L',
  'M', 'N', 'O', 'P', 'Q', 'R',
  'S', 'T', 'U', 'V', 'W', 'X',
  'Y', 'Z'
]


function alphabetSequence(i) {
  let prefix = ''
  const letterIteration = Math.ceil(i/26) - 2
  if(letterIteration >= 0) {
       prefix = letters[letterIteration];
  }
  
  let newIndex = i - ((letterIteration + 1) * 26)
  let letter = String.fromCharCode(newIndex+startCharCode)
  return `${prefix}${letter}`
}

for(let i=1; i<=30; i++) {
	const letter = alphabetSequence(i)
    console.log(letter)
}