@quantojs/music

Music for quanto: A4, B♭3, A4 +15¢, Fis4, Sol4 and 440 Hz parse into pitches, and 6/8, 3+2+2/8 and common time into time signatures.

import { pitch, timeSignature } from '@quantojs/music';

pitch().parse('B♭3');                                   // { value: 58, unit: 'note' } (MIDI)
pitch({ canonicalUnit: 'Hz' }).parse('A4 +15¢');         // { value: 443.83, unit: 'Hz' }
pitch().parse('B4', { locale: 'de-DE' });                // { value: 70, unit: 'note' }: B♭ in German
pitch().format({ value: 70, unit: 'note' });             // 'A♯4'
pitch().format({ value: 70, unit: 'note' }, { music: { key: 'F major' } });   // 'B♭4'
timeSignature().parse('3+2+2/8');                        // { numerator: 7, denominator: 8, groups: [3, 2, 2] }

• pitch() is a quantity in MIDI note numbers (note, with cents as the fraction) or Hz, so convert and compare from quanto/quantity work on it. Options: a4 (tuning, default 440), middleC (4, or 3 for the Yamaha and French numbering), defaultOctave, defaultUnit and canonicalUnit.
• Names follow the locale. German and Nordic H/B and -is/-es names, and solfège (Do Ré Mi), which reads everywhere. format prints the locale's names.
• ctx.music.key spells notes the way the key does (F major prints B♭, F# major prints E♯), with sharps by default. Set it once on the provider or per call; it only changes formatting.
• timeSignature(): 4/4, 6/8, additive meters, C, cut time, alla breve, 𝄴, 𝄵.
• Still evolving. Parse results may change between releases as the grammar grows. The full rules are in the repository's DESIGN.md.

quanto is a peer dependency.