Javascript taught Music Theory
Teoria.js is a lightweight and fast JavaScript library for music theory, both Jazz and Classical. It aims at providing an intuitive programming interface for music software (such as Sheet Readers, Sheet Writers, MIDI Players etc.).
A note object (teoria.Note
), which understands alterations, octaves,
key number, frequency and etc. and Helmholtz notation
A chord object (teoria.Chord
), which understands everything
from simple major/minor chords to advanced Jazz chords (Ab#5b9, F(#11) and such)
A scale object (teoria.Scale
), The scale object is a powerful presentation of
a scale, which supports quite a few handy methods. A scale can either be
constructed from the predefined scales, which by default contains the 7 modes
(Ionian, Dorian, Phrygian etc.) a major and minor pentatonic and the harmonic
chromatic scale or from an arbitrary array of intervals. The scale object
also supports solfège, which makes it perfect for tutorials on sight-reading.
An interval object (teoria.Interval
), which makes it easy to find the
interval between two notes, or find a note that is a given interval from a note.
There's also support for counting the interval span in semitones and inverting the
interval.
$ npm install teoria
Can be used with both Node and Browserify/webpack/etc.
Include the bundled build file, teoria.js
from this repository, directly:
<script src="path/to/teoria.js"></script>
This is just a short introduction to what teoria-code looks like, for a technical library reference, look further down this document.
// Create notes:
var a4 = teoria.note('a4'); // Scientific notation
var g5 = teoria.note("g''"); // Helmholtz notation
var c3 = teoria.note.fromKey(28); // From a piano key number
// Find and create notes based on intervals
teoria.interval(a4, g5); // Returns a Interval object representing a minor seventh
teoria.interval(a4, 'M6'); // Returns a Note representing F#5
a4.interval('m3'); // Returns a Note representing C#4
a4.interval(g5); // Returns a Interval object representing a minor seventh
a4.interval(teoria.note('bb5')).invert(); // Returns a Interval representing a major seventh
// Create scales, based on notes.
a4.scale('mixolydian').simple(); // Returns: ["a", "b", "c#", "d", "e", "f#", "g"]
a4.scale('aeolian').simple(); // Returns: ["a", "b", "c", "d", "e", "f", "g"]
g5.scale('ionian').simple(); // Returns: ["g", "a", "b", "c", "d", "e", "f#"]
g5.scale('dorian'); // Returns a Scale object
// Create chords with the powerful chord parser
a4.chord('sus2').name; // Returns the name of the chord: 'Asus2'
c3.chord('m').name; // Returns 'Cm'
teoria.chord('Ab#5b9'); // Returns a Chord object, representing a Ab#5b9 chord
g5.chord('dim'); // Returns a Chord object, representing a Gdim chord
// Calculate note frequencies or find the note corresponding to a frequency
teoria.note.fromFrequency(467); // Returns: {'note':{...},'cents':3.102831} -> A4# a little out of tune.
a4.fq(); // Outputs 440
g5.fq(); // Outputs 783.9908719634985
// teoria allows for crazy chaining:
teoria.note('a') // Create a note, A3
.scale('lydian') // Create a lydian scale with that note as root (A lydian)
.interval('M2') // Transpose the whole scale a major second up (B lydian)
.get('third') // Get the third note of the scale (D#4)
.chord('maj9') // Create a maj9 chord with that note as root (D#maj9)
.toString(); // Make a string representation: 'D#maj9'
name - The name argument is the note name as a string. The note can both
be expressed in scientific and Helmholtz notation.
Some examples of valid note names: Eb4
, C#,,
, C4
, d#''
, Ab2
coord - If the first argument isn't a string, but a coord array,
it will instantiate a Note
instance.
duration - The duration argument is an optional object
argument.
The object has two also optional parameters:
value
- A number
corresponding to the value of the duration, such that:
1 = whole
, 2 = half (minim)
, 4 = quarter
, 8 = eight
dots
- The number of dots attached to the note. Defaults to 0
.
A static method that returns an instance of Note set to the note at the given piano key, where A0 is key number 1. See Wikipedia's piano key article for more information.
A static method returns an object containing two elements:
note - A Note
which corresponds to the closest note with the given frequency
cents - A number value of how many cents the note is out of tune
note - A number ranging from 0-127 representing a MIDI note value
note - The name argument is the note name as a string. The note can both
be expressed in scientific and Helmholtz notation.
Some examples of valid note names: Eb4
, C#,,
, C4
, d#''
, Ab2
x
, #
, b
or bb
)x = 2, # = 1, b = -1, bb = -2
whitenotes - If this parameter is set to true
only the white keys will
be counted when finding the key number. This is mostly for internal use.
concertPitch - If supplied this number will be used instead of the normal concert pitch which is 440hz. This is useful for some classical music.
This allows for easy enharmonic checking:
teoria.note('e').chroma() === teoria.note('fb').chroma();
The chroma number is ranging from pitch class C which is 0 to 11 which is B
scaleName - The name of the scale to be returned. 'minor'
,
'chromatic'
, 'ionian'
and others are valid scale names.
Look at the documentation for teoria.interval
#interval
method, but changes this
note, instead of returning a newname - The name attribute is the last part of the chord symbol.
Examples: 'm7'
, '#5b9'
, 'major'
. If the name parameter
isn't set, a standard major chord will be returned.
Example: teoria.note('A5').helmholtz() -> "a''"
Example: teoria.note("ab'").scientific() -> "Ab4"
oneAccidental - Boolean, if set to true, only enharmonic notes with one accidental is returned. E.g. results such as 'eb' and 'c#' but not 'ebb' and 'cx'
teoria.note('c').enharmonics().toString();
// -> 'dbb, b#'
teoria.note('c').enharmonics(true).toString();
// -> 'b#'
scale - An instance of Scale
, which is the context of the solfege step measuring
showOctaves - A boolean. If set to true, a "Helmholtz-like" notation will be used if there's bigger intervals than an octave
Examples: teoria.note('A', 8).durationName() -> 'eighth'
,
teoria.note('C', 16).durationName() -> 'sixteenth'
D
in a C major scale will return 2
as it is the second degree of that scale.
If however the note isn't a part of the scale, the degree returned will be
0
, meaning that the degree doesn't exist. This allows this method to be both
a scale degree index finder and an "isNoteInScale" method.scale - An instance of Scale
which is the context of the degree measuring
dontShow - If set to true
the octave will not be included in the returned string.
root - A Note
instance which is to be the root of the chord
chord - A string containing the chord symbol. This can be anything from
simple chords, to super-advanced jazz chords thanks to the detailed and
robust chord parser engine. Example values:
'm'
, 'm7'
, '#5b9'
, '9sus4
and '#11b5#9'
name - A string containing the full chord symbol, with note name. Examples:
'Ab7'
, 'F#(#11b5)'
note - Instead of supplying a string containing the full chord symbol,
one can pass a Note
object instead. The note will be considered root in
the new chord object
octave - If the first argument of the function is a chord name (typeof "string"
),
then the second argument is an optional octave number (typeof "number"
) of the root.
symbol - A string containing the chord symbol (excluding the note name)
Note
that is the root of the chord.Note
s that the chord consists of.Array
of only the notes' names, not the full Note
objects.Interval
svoicing - An optional array of intervals in simple-format that represents the current voicing of the chord.
Here's an example:
var bbmaj = teoria.chord('Bbmaj7');
// Default voicing:
bbmaj.voicing(); // #-> ['P1', 'M3', 'P5', 'M7'];
bbmaj.notes(); // #-> ['bb', 'd', 'f', 'a'];
// New voicing
bbmaj.voicing(['P1', 'P5', 'M7', 'M10']);
bbmaj.notes(); // #-> ['bb', 'f', 'a', 'd'];
NB: Note that above returned results are pseudo-results, as they will be
returned wrapped in Interval
and Note
objects.
'major'
, 'minor'
,
'augmented'
, 'diminished'
, 'half-diminished'
, 'dominant'
or undefined
interval - A string name of an interval, for example 'third'
, 'fifth'
, 'ninth'
.
additional - Additional chord extension, for example: 'b9'
or '#5'
additional - Like the dominant's.
additional - Like the dominant's
'dyad'
, 'triad'
, 'trichord'
,
'tetrad'
or 'unknown'
.interval
away#interval
method, except it's this
chord that gets changed instead of
returning a new chord.tonic - A Note
which is to be the tonic of the scale
scale - Can either be a name of a scale (string), or an array of absolute intervals that defines the scale. The scales supported by default are:
Scale
objectstring
or undefined
Note
which is the scale's tonicNote
s which is the scale's notesArray
of only the notes' names, not the full Note
objects.index - Can be a number referring to the scale step, or the name (string) of the scale step. E.g. 'first', 'second', 'fourth', 'seventh'.
index Same as Scale#get
showOctaves - A boolean meaning the same as showOctaves
in Note#solfege
#from
and #between
methods of the same namespace and
for creating Interval
objects.string
: from)Interval.toCoord
functionNote
: from, string
: to)Interval.from
functionNote
: from, Interval
: to)Interval
instead of a string representation of
the intervalNote
: from, Note
: to)Interval.between
functionInterval
representing the interval expressed in string form.from - The Note
which is the root of the measuring
to - A Interval
from and to are two Note
s which are the notes that the
interval is measured from. For example if 'a' and 'c' are given, the resulting
interval object would represent a minor third.
Interval.between(teoria.note("a"), teoria.note("c'")) -> teoria.interval('m3')
simpleInterval - An interval represented in simple string form. Examples:
'm' = minor
, 'M' = major
, 'A' = augmented
and
'd' = diminished
The number may be prefixed with a -
to signify that its direction is down. E.g.:
m-3
means a descending minor third, and P-5
means a descending perfect fifth.
'P5'
,
'M3'
, 'A9'
, etc.'perfect'
(1, 4, 5, 8) or 'minor'
(2, 3, 6, 7)'dd'
, 'd'
'm'
, 'P'
, 'M'
, 'A'
or 'AA'
)verbose is set to a truish value, then long quality names are returned:
'doubly diminished'
, 'diminished'
, 'minor'
, etc.
dir - If supplied, then the interval's direction is to the newDirection
which is either 'up'
or 'down'
number
of semitones the interval span.ignoreDirection - An optional boolean that, if set to true
, returns the
"direction-agnostic" interval. That is the interval with a positive number.
teoria.interval('M17').simple(); // #-> 'M3'
teoria.interval('m23').simple(); // #-> 'm2'
teoria.interval('P5').simple(); // #-> 'P5'
teoria.interval('P-4').simple(); // #-> 'P-4'
// With ignoreDirection = true
teoria.interval('M3').simple(true); // #->'M3'
teoria.interval('m-10').simple(true); // #-> 'm3'
NB: Note that above returned results are pseudo-results, as they will be
returned wrapped in Interval
objects.
interval
to this interval, and returns a Interval
representing the result of the additioninterval
is equal to this intervalinterval
is greater than this intervalinterval
is smaller than this intervalInterval