Octavian

Octavian is a little utility library for working with musical notes and their frequencies. Super cool, right?

Installation

First things, first: how do I install this thing?

``js
npm install octavian
`

Maybe you even throw a --save in there if you feel like keeping it around.

Usage

So, we've got Octavian installed, how do we use it?

`js
var Octavian = require('octavian');

var note = new Octavian.Note('A4');
`

Or, if you're some kind of hipster…

`js
var Note = require('octavian').Note;

var note = new Note('A4');
`

$3

A Note has a few properties that we can play around with.

`js
var note = new Note('A#4');

note.letter; // 'A'
note.modifier; // '#'
note.octave; // 4
note.signature; // 'A#4'
note.pianoKey; // 50
note.frequency; // 466.164
`

$3

But, what if we toss in some bogus note? Something like E#, maybe? There is no E#, right?

`js
var note = new Note('E#5');

note.signature; // 'F5'
`

$3

Music is all about intervals. We can move up by a semitone or some other interval.

`js
var note = new Note('C3');

note.majorThird(); // returns a new Note('E3');
note.perfectFifth(); // returns a new Note('G3');
note.perfectOctave(); // returns a new Note('C4');
`

You can do any of the following:

* downOctave()
* minorSecond()
* majorSecond()
* minorThird()
* majorThird()
* perfectFourth()
* diminishedFifth()
* perfectFifth()
* minorSixth()
* majorSixth()
* minorSeventh()
* majorSeventh()
* perfectOctave()

There are also some extra methods that are aliased, if you'd prefer:

* augmentedFourth()
* third()
* fifth()

$3

You can create chords with Octavian.

`js
const cMajorChord = new Octavian.Chord('C4', 'major');

cMajorChord.notes; // returns [ { letter: 'C', modifier: null, octave: 4 },
// { letter: 'E', modifier: null, octave: 4 },
// { letter: 'G', modifier: null, octave: 4 } ]

cMajorChord.signatures; // returns [ 'C4', 'E4', 'G4' ]
cMajorChord.frequencies; // returns [ 261.626, 329.628, 391.995 ]
cMajorChord.pianoKeys; // returns [ 40, 44, 47 ]
`

You can create the following chords:

* major
* majorSixth
* majorSeventh
* majorSeventhFlatFive
* majorSeventhSharpFive
* minor
* minorSixth
* minorSeventh
* minorMajor
* dominantSeventh
* diminished
* diminishedSeventh
* halfDimished

You're also more than welcome to use the following aliases for any of the above:

* maj is an alias for major
* 6 is an alias for majorSixth
* maj6 is an alias for majorSixth
* 7 is an alias for majorSeventh
* maj7 is an alias for majorSeventh
* maj7b5 is an alias for majorSeventhFlatFive
* maj7#5 is an alias for majorSeventhSharpFive
* min is an alias for minor
* m is an alias for minor
* min6 is an alias for minorSixth
* m6 is an alias for minorSixth
* min7 is an alias for minorSeventh
* m7 is an alias for minorSeventh
* m#7 is an alias for minorMajor
* min#7 is an alias for minorMajor
* m(maj7) is an alias for minorMajor
* dom7 is an alias for dominantSeventh
* dim is an alias for diminished
* dim7 is an alias for diminishedSeventh
* m7b5 is an alias for halfDiminshed

#### Adding Notes to a Chord

You can add notes to a chord manually, if that suits you:

`js
const chord = new Octavian.Chord('C4');

chord.signatures; // returns ['C4']

chord.addInterval('majorThird');
chord.signatures; // returns ['C4', 'E4']

chord.addInterval(7);
chord.signatures; // returns ['C4', 'E4', 'G4']
`

#### Turning a Note into a Chord

You can turn any note into the basis for a chord:

`js
const note = new Octavian.Note('C4');
note.toChord(); // returns a new chord with only C4 in it.
note.toChord('major'); // returns a new chord with C4, E4, and G4 in it
``