tonal.note is collection of functions to manipulate notes:

var note = require('tonal.note')
distance('C3', '3m') // => 'Eb3'

It's part of tonal

• Midi and frequencies: midi, freq, fromMidi
• Note properties: pitchClass, setOctave
• Enharmonics: enharmonics
• Transposition and distances: transpose, distance

Only via npm: npm i --save tonal.note

Notes in tonal are represented by strings, and by default it uses scientific notation with the form: letter[accidentals][octave]/[duration].

Pitch classes are note names without octave and duration. They are used a lot to describe pitch sets like scales.

The note function returns a scientific notation of the given string or null if not valid string. It can be used to check if some string is a note:

// get a note
note('c2') // => 'C2'
note('fx') // => 'F##'
note('blah') // => null
// filter notes
['e', 'f', 'g', 'h', 'i'].filter(note) // => ['e', 'f', 'g']

There are several functions to get note properties or to modify them:

// get properties
note.octave('C#4') // => 4
note.pitchClass('Bb5/4') // => 'Bb'

// set properties
note.setOctave(3, 'Bb0') // => 'Bb3'

#### Midi and frequencies

You can transform to midi and frequencies:

note.midi('A4') // => 69
note.fromMidi(13) // => 'Bb0'
note.freq(null, 'A4') // => '440'

The note.enharmonics function return the nearest enharmonics of a note:

note.enharmonics('C') // => ['B#', 'C', 'Dbb']

#### Note transposition

You can transpose notes with the note.transpose function. The order of the parameters doesn't matter:

transpose('C2', '4A') // => 'F#2'
transpose('4A', 'C2') // => 'F#2'

If you transpose pitch classes (note names without octaves), the returned value will be a pitch class:

tranpose('A', '3M') // => 'C#'
tranpose('A5', '3M') // => 'C#5'

Also, you can partially apply the function to get a transposer:

var major3th = transpose('3M')
major3th('D') // => 'F#'

Transposers allows to work with arrays seamlessly:

['C', 'D', 'E', 'F', 'G'].map(transpose('3M')) // => ['E', 'F#', 'G#', 'A', 'B']
['1P', '3m', '5P'].map(transpose('C')) // => ['C', 'Eb', 'G']

The note.distance function get the interval between two notes:

note.distance('C2', 'D2') // => '2M'

Read the generated documentation or take a look at tonal

MIT License