Muso Dojo | Music Theory Data

A type-safe TypeScript/JavaScript library of music theory data and helpers for music apps, education tools, practice tools, and creative coding projects.

It includes typed datasets for notes, intervals, scales, modes, chord pitch collections, chord progressions, string instrument tunings, note colors, MIDI helpers, and naming utilities.

What's Included

• Note collections: notes, dyads, scales, modes, arpeggios, and chord pitch collections, grouped into families such as diatonic modes, pentatonic variants, major/minor/dominant variants, harmonic minor modes, melodic minor modes, diminished variants, and augmented variants.
• Chord progressions: 4-bar foundational loops, 8-bar loops, and 12-bar blues progressions with roman symbols, scale degrees, qualities, and bar durations.
• Labels and theory primitives: note names, root notes, intervals, chromatic indexes, roman numerals, chord qualities, and conversion helpers.
• Application helpers: note-name generation, interval transforms, chord progression resolution, chord spelling, MIDI helpers, note colors, contrast helpers, and string instrument tunings.
• TypeScript-first API: exported data, utility functions, and types are designed to work well with autocomplete and compile-time checking.

For exhaustive data, types, and function signatures, use the JSR API documentation. The tests/ directory also contains practical examples of supported behavior.

Package Registries

• JSR package
• npm package

Installation

Deno / JSR

deno add jsr:@musodojo/music-theory-data

import * as musicTheoryData from "jsr:@musodojo/music-theory-data";

Node.js / npm

npm install @musodojo/music-theory-data

import * as musicTheoryData from "@musodojo/music-theory-data";

Usage

Get Note Names

import * as musicTheoryData from "jsr:@musodojo/music-theory-data";

const aHarmonicMinor = musicTheoryData.getNoteNamesForRootAndNoteCollectionKey(
  "A",
  "harmonicMinor",
);

console.log(aHarmonicMinor);
// ["A", "B", "C", "D", "E", "F", "G♯", "A"]

const fMajor = musicTheoryData.getNoteNamesForRootAndNoteCollectionKey(
  "F",
  "ionian",
);

console.log(fMajor);
// ["F", "G", "A", "B♭", "C", "D", "E", "F"]

Inspect A Note Collection

import {
  groupedNoteCollections,
  noteCollections,
} from "jsr:@musodojo/music-theory-data";

const ionian = noteCollections.ionian;

console.log(ionian.primaryName);
// "Major"

console.log(ionian.intervals);
// ["1", "2", "3", "4", "5", "6", "7", "8"]

console.log(Object.keys(groupedNoteCollections));
// ["diatonicModes", "pentatonicVariants", ...]

Each collection includes structured fields such as names, intervals, integer notation, type tags, and musical characteristics. See the generated docs or source files for complete schemas.

Resolve Chord Progressions

import {
  chordProgressions,
  getChordProgressionChordNames,
  getChordProgressionRomanSymbols,
  getChordProgressionTotalDurationInBars,
} from "jsr:@musodojo/music-theory-data";

const oneSixFourFive = chordProgressions.oneSixFourFive;

console.log(oneSixFourFive.chords.map((chord) => chord.romanSymbol));
// ["I", "vi", "IV", "V"]

console.log(getChordProgressionRomanSymbols("oneSixFourFive"));
// ["I", "vi", "IV", "V"]

console.log(getChordProgressionChordNames("C", "oneSixFourFive"));
// ["CM", "Am", "FM", "GM"]

console.log(getChordProgressionTotalDurationInBars("twelveBarBlues"));
// 12

Use Note Colors And Chromatic Indexes

import {
  colorCollections,
  getNoteColorIndex,
  getNoteColorLabels,
} from "jsr:@musodojo/music-theory-data";

const absoluteIndex = getNoteColorIndex({
  midi: 67,
  mode: "absolute",
});

console.log(absoluteIndex);
// 7, the pitch class G

const relativeIndex = getNoteColorIndex({
  midi: 69,
  mode: "relative",
  rootPitchClass: 2,
});

console.log(relativeIndex);
// 7, A as the fifth above D

console.log(getNoteColorLabels(colorCollections.musoDojoRootAndFifth));
// ["1", "♭2", "2", "♭3", "3", "4", "♭5", "5", "♭6", "6", "♭7", "7"]

Note color collections use 12 chromatic slots. Absolute mode treats index 0 as C; relative mode treats index 0 as the chosen musical root.

API Documentation

For the full list of available data, types, and utility functions, see the auto-generated API documentation on JSR.

Community & Support

• Ask questions or share ideas in GitHub Discussions.
• Report bugs or data issues in GitHub Issues.