Interval-parser NPM

interval-parser

Parses music intervals in shorthand notation:

var parser = require('interval-parser')
parser.parse('P4')
// => { num: 4, q: 'P', dir: 1, simple: 4, type: 'P', alt: 0, oct: 0, semitones: 5 }

// accepts reverse shorthand notation
parser.parse('6m')
// => { num: 6, q: 'm', dir: 1, simple: 6, type: 'M', alt: -1, oct: 0, semitones: 8 }

If you only need a property, you can use a function with the property name:

parser.semitones('6m') // => 8
parser.simple('9M') // => 2

#### Interval string format

It accepts two different interval string formats:

In standard shorthand notation: quality+[dir]+num. Examples: 'P8', 'M-3'
In reverse shorthand notation: [dur]+num+quality. Examples: '8P', '-3M'

API

`parse(str)`

Parse a string with an interval in shorthand notation and returns an object with interval properties

Parameters

str String the string with the interval

Examples

var parser = require('interval-parser')
parser.parse('P4')
// => { num: 4, q: 'P', dir: 1, simple: 4, type: 'P', alt: 0, oct: 0, semitones: 5 }
// accepts reverse shorthand notation
parser.parse('6m')
// => { num: 6, q: 'm', dir: 1, simple: 6, type: 'M', alt: -1, oct: 0, semitones: 8 }

Returns an object with interval properties or null if not valid interval string:

num: the interval number
q: the interval quality string (M is major, m is minor, P is perfect...)
simple: the simplified number (from 1 to 7)
dir: the interval direction (1 ascending, -1 descending)
type: the interval type (P is perfectable, M is majorable)
alt: the alteration, a numeric representation of the quality
oct: the number of octaves the interval spans. 0 for simple intervals.
semitones: the size of the interval in semitones

Helper functions

For each property of the interval there's a function with the same name that returns only that property:

parser.num('9m') // => 9
parser.q('9m') // => 'm'
parser.simple('9m') // => 2
parser.dir('9m') // => 1
parser.type('9m') // => 'M'
parser.alt('9m') // => -1
parser.oct('9m') // => 1
parser.semitones('9m') // => 13