Harmonie

Harmonie is a typescript library that solves music theory questions such as adding & subtracting intervals from a given note, calculating scales, chords and more... Harmonie is written without any third party libraries for minimal bundle size.

Installation

@davidfloegel/harmonie is serverd as an npm package.

Add Harmonie to your project by running

// with npm
npm add @davidfloegel/harmonie

// with yarn
yarn add @davidfloegel/harmonie

To Do List

• Clean up & restructure test suite
• Add commitlint
• Publish to NPM
• Add JSDOC
• Add chords
• Add more scales
• Add key signatures
• Add transpose function
• Add compound intervals

Usage

Notes

Creating a note

// by name with default octave
const noteEb = new Note('Eb')

// change octave
const noteD5 = new Note('D', 5)

Properties

const noteEb = new Note('Eb')

noteEb.letter // E
noteEb.accidentals // b
noteEb.octave // 4
noteEb.midiValue // 63

Enharmonic Equivalent

Sometimes (mostly in classical music) you will come across notations such as Fb, B#. While this is technically correct, in most modern music an Fb would be written as E, B# as C etc. This is called the enharmonic equivalent. To get the enharmonic equivalent of a note you can use the easyNotation property.

const note = new Note(B#)
note.easyNotation // C

Intervals

Creating an interval

// by quality and quantity
const P4 = new Interval('P', 4)

// from string
const M3 = Interval.fromString('M3')

Properties

const interval = new Interval('m', 6)

interval.name // m6
interval.fullName // minor 6
interval.quality // m
interval.quantity // 6
interval.semitones // 8

Inverting an interval

const interval = new Interval('M', 3)
const inversion = interval.invert()

inversion.name // 'm6'

Adding an interval to a note

const root = new Note('E')
const interval = Interval.fromString('P5')

const target = root.addInterval(interval)
target.name // B

Subtracting an interval from a note

const root = new Note('E')
const interval = Interval.fromString('P5')

const target = root.addInterval(interval)
target.name // A

Determining the interval between two notes

const noteA = new Note('D')
const noteB = new Note('B')

const interval = noteA.minusNote(noteB)
interval.name // M6