note-parser 

 

Parse note names (in scientific notation) with javascript. Given a string, obtain a hash
with note properties (including midi number and frequency)

If you need parse interval names take a look to interval-notation

Usage

Install via npm: npm i --save note-parser and require it:

``js
var parser = require('note-parser')
parser.parse('c#4') // => { letter: 'C', acc: '#', ... midi: 61, freq: 277.1826309768721 }
`

The returned object will contain:

- letter: the uppercase letter of the note
- acc: the accidentals of the note (only sharps or flats)
- pc: the pitch class (letter + acc)
- step: s a numeric representation of the letter. It's an integer from 0 to 6 where 0 = C, 1 = D ... 6 = B
- alt: a numeric representation of the accidentals. 0 means no alteration,
positive numbers are for sharps and negative for flats
- chroma: a numeric representation of the pitch class. It's like midi for
pitch classes. 0 = C, 1 = C#, 2 = D ... It can have negative values: -1 = Cb.

If the note name has octave, the returned object will additionally have:

- oct: the octave number (as integer)
- midi: the midi number
- freq: the frequency (using tuning parameter as base)

If the parameter isTonic is set to true another property is included:

- tonicOf: the rest of the string that follows note name (left and right trimmed)

#### Midi note number and frequency

If you are interested only in midi numbers or frequencies, you can use midi function:

`js
parser.midi('A4') // => 69
parser.midi('blah') // => null
parser.midi(60) // => 60
parser.midi('60') // => 60
`

or the freq function:

`js
parser.freq('A4') // => 440
parser.freq('A3', 444) // => 222
parser.freq(69) // => 440
`

$3

With the build function you can convert back to string:

`js
parser.build(parser.parse('cb2')) // => 'Cb2'
`

Alternatively the build function accepts step, alteration, octave parameters:

`js
parser.build(3, -2, 4) // => 'Fbb4'
`

## Tests and documentation

You can read the generated API documentation here

To run the test clone this repo and:

`
npm install
npm test
``

License

MIT License