scale-maker

Returns a variety of musical scales as arrays of values (as frequency in Hertz or cents for use as a detune) for use in the Web Audio Javascript API and other Javascript-based audio environments.

Demo page

http://davidcole1977.github.io/scale-maker/demo/

Getting started (NPM / Node)

Install using npm

npm install scale-maker --save

Once the module is installed, include it in your JS code using require()

var ScaleMaker = require('scale-maker');

Getting started (Bower)

Install using bower

bower install scale-maker --save

Once the module is installed, include it in your HTML page

<script src="bower_components/scale-maker/lib/scaleMaker.min.js"></script>

and then refer to it in your Javscript as ScaleMaker, eg.

var myScaleInHertz = ScaleMaker.makeScale('minorPentatonic', 'F#5', 9).inHertz;

Alternatively, you can include it using Node JS or Browserify

var ScaleMaker = require('./bower_components/scale-maker/lib/node/scaleMaker.min.js');

Basic usage

var ScaleMaker = require('scale-maker'); // skip this line if you're including the module using an HTML script tag
 
// create a minor pentatonic scale over 2 octaves (9 notes), starting on F# in the
// 5th octave and get the value of the notes in hertz
var myScaleInHertz = ScaleMaker.makeScale('minorPentatonic', 'F#5', 9).inHertz;
 
// adds a new scale type called 'myWeirdScale'
ScaleMaker.addScale('myWeirdScale', [1, 2, 2, 3, 1, 2]);
 
// which can now be used to create a new scale (this time in cents rather than hertz)
var myWeirdScaleInCents = ScaleMaker.makeScale('myWeirdScale', 'Ab4', 13).inCents;
 
// gets the frequency of a G flat in the 3rd octave
var myNoteInHertz = ScaleMaker.getNote('Gb3');

Methods

makeScale(scaleType, startNote, noteCount)

Given a start note, the type of scale and the number of notes in the scale, returns an object with three arrays: the note values in hertz, cents and semitone intervals.

Arguments

scaleType (String) string representing the type of scale. eg. 'major', 'chromatic', etc.

Possible values:

• 'major'
• 'naturalMinor'
• 'harmonicMinor'
• 'melodicMinor'
• 'chromatic'
• 'wholeTone'
• 'majorPentatonic'
• 'minorPentatonic'
• 'kuomiPentatonic'
• 'chinesePentatonic'

startNote (String) The note name, flat or sharp flag, and octave number of the first note of the scale expressed as a 2 or 3 character string, eg:

• 'Ab5' is the note A flat in the 5th octave
• 'C0' is the note C in the bottom octave
• 'F#8' is the note F sharp in the 8th octave

The lowest note allowed is 'C0' The highest note allowed is 'B8'

noteCount (Integer) The number of notes you'd like in the scale. For instance if you want two octaves of a major scale, that's 15 notes.

Returns

(Object) Object with three parameters, each an array representing the value of notes in hertz, cents and semitone intervals. For example, if requesting a major scale with 8 notes, starting on C in the 4th octave, the return value would be:

{
  inHertz: [261.63, 293.67, 329.63, 349.23, 392.00 440.01, 493.89, 523.26],
  inCents: [0, 200, 400, 500, 700, 900, 1100, 1200],
  inSemiTones: [0, 2, 4, 5, 7, 9, 11, 12]
}

Note: the note values in cents and semitones are relative to the start note, which is why the start note always has a value of 0.

Example usage

// create a minor pentatonic scale over 2 octaves (9 notes), starting on F# in the 5th octave and get the value of the notes in hertz
var myScaleInHertz = ScaleMaker.makeScale('minorPentatonic', 'F#5', 9).inHertz;
 
// the same scale, this time in cents for use as a detune
var myScaleInCents = ScaleMaker.makeScale('minorPentatonic', 'F#5', 9).inCents;
 
// the same scale, this time in semitone intervals
var myScaleInSemiTones = ScaleMaker.makeScale('minorPentatonic', 'F#5', 9).inSemiTones;

---

getNote(note)

Given a musical note, expressed as a string, returns the value of that note in hertz, where A4 is 440Hz.

Arguments

note (String) The note name, flat or sharp flag, and octave number of the note expressed as a 2 or 3 character string, eg:

• 'Ab5' is the note A flat in the 5th octave
• 'C0' is the note C in the bottom octave
• 'F#8' is the note F sharp in the 8th octave

The lowest note allowed is 'C0' The highest note allowed is 'B8'

Returns

(Number) The frequency value of the note in hertz.

Example usage

// gets the frequency of a G flat in the 3rd octave
var myNoteInHertz = ScaleMaker.getNote('Gb3');

---

addScale(name, intervals)

Given a name and array of semitone intervals, creates a new scale type, which you can then use to create a scale using makeScale().

Arguments

name (String) String representing the type of scale, which will then be used to reference the scale when creating a scale using makeScale().

intervals (Array) Array of integers representing the semitone intervals between each note in a single, whole octave of the scale. For instance, a major scale would be expressed as

[2, 2, 1, 2, 2, 2, 1]

Example usage

// adds a new scale type called 'myWeirdScale'
ScaleMaker.addScale('myWeirdScale', [1, 2, 2, 3, 1, 2]);
 
// which can now be used to create a new scale
var myWeirdScaleInCents = ScaleMaker.makeScale('myWeirdScale', 'Ab4', 13).inCents;

---

getScaleNames()

Returns the names of all available scales, as an array of strings

Returns

(Array) The names of all built in and user-created scales, as an array of strings

Example usage

// adds a new scale type called 'myWeirdScale'
ScaleMaker.addScale('myWeirdScale', [1, 2, 2, 3, 1, 2]);
 
// gets the names of available scales, including the scale that was just added
var allScales = ScaleMaker.getScaleNames();
 
// allScales === ['chromatic', 'wholeTone', 'major', 'majorPentatonic', 'minorPentatonic', 'kuomiPentatonic', 'chinesePentatonic', 'naturalMinor', 'harmonicMinor', 'melodicMinor', 'myWeirdScale'];
 

Development

Dependencies

• grunt
• node

Mocha unit tests live in test/

Set up

$ npm install

Running the grunt tasks

#linting, unit tests, compression 
$ grunt

See gruntfile.js for more details of the grunt tasks

Known Issues

• Incompatible with Internet Explorer versions 8 and below

Todo

• demo page: use on-screen keyboard to play a scale – code example updates in realtime as you play, with code to make the scale you're playing
• add to function outputs: makeScale as note names; makeScale & getNote as midi note values
• option to specify number of octaves as well as number of notes

Version history

0.2.2

• Added code coverage with Istanbul and Coveralls

0.2.1

• Added Travis CI support, including build status image in readme file

0.2.0

• Added new public getScaleNames() method to return all available scale names as an array

0.1.1

• Corrected reference to module in mocha unit tests

0.1.0

• Now available as a Bower component and NPM module

0.0.12

• created bower.json file

0.0.11

• automatically generate non-node version of ScaleMaker module

0.0.10

• added the remaining minor scales
• corrected code typo on demo page
• updated scales used on demo page
• optimised getNote unit tests

0.0.9

• removed browserify
• updated demo page to not use common js modules

0.0.8

• added demo page
• added scale settings to example scales
• reduced duplication in test spec
• added browserify to grunt build (for demo page)

0.0.7

• moved main file into lib/ and corresponding updates to build & test files

0.0.6

• changed name to scaleMaker / scale-maker

0.0.5

• added input error handling for public API functions

0.0.4

• removed unnecessary ScaleMaker constructor function
• added input validation functions isValidNoteName(), isValidScaleName(), isValidScaleDefinition(), isScaleTypeDefined(), isPositiveIntegerGreaterThanZero() (not yet incorporated into public API functions)
• added JS compression to grunt build

0.0.3

• changed function names getScale() to makeScale() and getNoteByName() to getNote()
• divided exported functions into functions exported for testing purposes and functions exported as part of the public API
• added new addScale() function

0.0.2

• getScale() now returns result in hertz, semitones and cents
• removed test scale & note references into a separate module

0.0.1

• Initial commit; grunt, jshint & mocha tests hooked up