(De-)cipher caesar encryption

caesar-code.ts

const alphabet = "abcdefghijklmnopqrstuvwxyz"

function caesar(input: string, offset: number): string {
  const result: string[] = []

  for (const character of input) {
    // Calculate caesar offset
    let offsetIndex: number = alphabet.indexOf(character) + offset

    // Move indices that are out of bounds back in
    if (offsetIndex < 0) offsetIndex = alphabet.length + offsetIndex
    if (offsetIndex > alphabet.length)
      offsetIndex = offsetIndex - alphabet.length

    // Keep spaces, convert all control characters (i.e. \n or \t) to spaces
    let char: string = character

    if (/\s/iu.test(character)) char = " "
    else char = alphabet.charAt(offsetIndex)

    result.push(char)
  }

  return result.join("")
}

const input: string =
  "cebtenzzvrerafvrvzzrefbnyfjnrerqreglcqreqrapbqrcsyr" +
  "\n" +
  "trazhffrvatrjnygorervgrecflpubcnguqrejrvffjbfvrjbuara"

console.log("Input:", input)

for (let i = -1; i > -alphabet.length; i--) {
  console.log(`Offset: ${i}\tmsg: ${caesar(input, i)}`)
}