music-tools

Utilities for music stuff: a small TypeScript library of four music theory classes — Note, Interval, Chord and Key.

Each one parses from a handful of representations (strings like C#4, m7, Cmaj7 or Eb major, MIDI numbers, semitone counts) and knows how to transpose, invert and compare itself. Spelling is preserved rather than normalized, so C transposed by an augmented fourth gives F#, not Gb.

import { Chord, Interval, Key, Note } from '@nilscox/music-tools';

new Note('C4').transpose(new Interval('M3')).toString(); // 'E4'
new Note('C4').transpose(new Interval('M3'), 'down').toString(); // 'Ab3'
new Note('C#').isEnharmonic(new Note('Db')); // true
new Chord('Am7').notes.map(String); // ['A', 'C', 'E', 'G']
new Chord('C/E').inversion; // 1
new Key('Eb major').accidentals.map(String); // ['Bb', 'Eb', 'Ab']
new Key('Eb major').relative.toString(); // 'C minor'

Install

pnpm add @nilscox/music-tools