https://github.com/mrfrac/goodchords

Music theory library
https://github.com/mrfrac/goodchords

chord interval music music-theory note pitch scale tone

Last synced: 11 months ago
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Music theory library

• Host: GitHub
• URL: https://github.com/mrfrac/goodchords
• Owner: mrfrac
• License: mit
• Created: 2018-11-30T13:12:40.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2025-06-09T22:59:42.000Z (about 1 year ago)
• Last Synced: 2025-06-11T22:19:14.641Z (about 1 year ago)
• Topics: chord, interval, music, music-theory, note, pitch, scale, tone
• Language: TypeScript
• Homepage:
• Size: 2.03 MB
• Stars: 7
• Watchers: 1
• Forks: 0
• Open Issues: 15
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# Goodchords

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> Music theory library

**The project is under development.**

## Usage

### Install

```bash

npm install --save goodchords

```

or

```bash

yarn add goodchords

```

### Import (ES6)

```js

import { Scale, Chord, Interval, Note } from "goodchords";

```

### Require (ES5)

```js

const { Scale, Chord, Interval, Note } = require("goodchords");

```

### Browser

Usage example:

```html

  

    Goodchords

    

    

      alert(window.goodchords.Note.fromString("A4").frequency());

    

  

```

> Replace X with correct version

### API

#### Note

```js

const note = new Note("A", "#", 4);

// or

const note = Note.fromString("A#4");

note.transpose("M3").toString(); // C##5

note.toString(); // A#4

note.frequency(); // 466.16

note.distanceTo("A#5"); // 12

note.number(); // 58

```

#### Interval

```js

const interval = new Interval(8, "P");

// or

const interval = Interval.fromString("8P"); // or P8

interval.semitones(); // 12

interval.isValid(); // true

interval.isCompound(); // false

Note.fromString("A4").transpose(interval).toString(); // A5

```

#### Scale

```js

const majorScaleFormula = ["P1", "M2", "M3", "P4", "P5", "M6", "M7"];

const scale = new Scale("A", majorScaleFormula);

scale.getNotes().map((note) => note.toString()); // ["A4", "B4", "C#5", "D5", "E5", "F#5", G#5", ]

const ionian = new Scale("C", "ionian");

ionian.getNotes().map((note) => note.toString()); // ["C4", "D4", "E4", "F4", "G4", "A4", "B4", ]

ionian.getChords(); // get chords for scale by degree

ionian.getScaleInfo(); // { name: "Major", formula: "<...>", altNames: ["Bilaval theta", "Ethiopian (A raray)", "Ionian", "Mela Dhirasankarabharana (29)", ]}

```

#### Chords

```js

const chord = new Chord("C", "m");

// or

const chord = Chord.fromString("Cm");

chord.getNotes(); // ["C4", "Eb4", "G4"]

```