Song Encryption (Final Exam 240719)

function solve(input) {
  const namePattern = /^[A-Z][a-z ']+$/m;
  const songPattern = /^[A-Z\s]+$/gm;

  const encrypt = (name, key) => {
    let str = "";
    for (const letter of name) {
      let newcode = letter.charCodeAt() + key;
      if (letter.charCodeAt() > 64 && letter.charCodeAt() < 91) {
        //A-Z
        if (newcode > 90) {
          let diff = newcode - 90;
          newcode = 64 + diff;
        }
        str += String.fromCharCode(newcode);
      } else if (letter.charCodeAt() > 96 && letter.charCodeAt() < 123) {
        //a-z
        if (newcode > 122) {
          let diff = newcode - 122;
          newcode = 96 + diff;
        }
        str += String.fromCharCode(newcode);
      } else {
        str += letter;
      }
    }
    return str;
  };

  for (const line of input) {
    if (line === "end") {
      break;
    }
    let [artist, song] = line.split(":");
    artist = artist.trim();
    song = song.trim();
    if (
      artist.match(namePattern) !== null &&
      song.match(songPattern) !== null
    ) {
      let key = artist.length;
      let encName = encrypt(artist, key);
      let encSong = encrypt(song, key);
      console.log(`Successful encryption: ${encName}@${encSong}`);
    } else {
      console.log(`Invalid input!`);
    }
  }
}