transpose.ts

/* To be used with Deno as a CLI utility
 * Trasposes a note a given number of semitones
 * E.G: `deno transpose.ts D# 15`
 *                              -> E
 */

const notes = [
  "A",
  "Bb",
  "B",
  "C",
  "C#",
  "D",
  "D#",
  "E",
  "F",
  "F#",
  "G",
  "G#",
];

const transpose = ([note, sNum]: [string, string]) => {
  if (isNaN(+sNum)) throw Error("invalid number");
  if (!notes.includes(note)) throw Error("Invalid note");
  const noteIndex = notes.indexOf(note);
  const num = +sNum;
  console.log(notes[(noteIndex + num) % notes.length]);
};

if (Deno.args.length === 2) transpose([Deno.args[0], Deno.args[1]]);

Thanks for the code:
Im trying to make one code that transpose chords.
Can you translate this to C#.
Thanks

@Cafony sadly I do not know or care to learn new OOP languages but it should be trivial enough! If you have any questions about how the code works, send them my way!