@tonaljs/interval

A collection of functions to create and manipulate music intervals

Usage

ES6:

import { Interval } from "tonal";

nodejs:

const { Interval } = require("tonal");

API

Interval.get(name: string)

Get properties of an interval:

• name: the interval name (number + quality)
• type: "perfectable" | "majorable"
• dir: direction: 1 | -1
• num: the interval number
• q: quality (...| 'dd' | 'd' | 'm' | 'M' | 'A' | ...)
• alt: the quality number as a number
• oct: the number of octaves it spans
• semitones: the number of semitones it spans
• simple: the simplified number

Interval.get("5P"); // => { name: "5P", num: 5, ...}

There are some shorthand functions (name, num, semitones, quality):

Interval.name("d4"); // => "4d"
Interval.num("5P"); // => 5
Interval.quality("5P"); // => "P"
Interval.semitones("P4"); // => 5

distance(from: string, to: string) => string

Find the interval between two notes.

Interval.distance("C4", "G4"); // => "5P"

names() => string[]

Return a list of (natural) interval names:

Interval.names(); // => ["1P", "2M", "3M", "4P", "5P", "6m", "7m"]

fromSemitones(semitones: number) => string

Given a number of semitones, returns the interval name:

Interval.fromSemitones(7); // => "5P"
Interval.fromSemitones(-7); // => "-5P"

[0, 1, 2, 3, 4].map(Interval.fromSemitones);

simplify(interval: string) => string

Simplify an interval:

Interval.simplify("9M"); // => "2M"
Interval.simplify("2M"); // => "2M"
Interval.simplify("-2M"); // => "7m"
["8P", "9M", "10M", "11P", "12P", "13M", "14M", "15P"].map(Interval.simplify);
// => [ "8P", "2M", "3M", "4P", "5P", "6M", "7M", "8P" ]

invert(interval: string) => string

Get the interval inversion:

Interval.invert("3m"); // => "6M"
Interval.invert("2M"); // => "7m"

add(a: string, b: string) => string

Add two intervals:

Interval.add("3m", "5P"); // => "7m"

subtract(min: string, sub: string) => string

Substract two intervals:

subtract("5P", "3M"); // => '3m'
subtract("3M", "5P"); // => '-3m'