Leiter

Leiter is a TypeScript-based library designed to generate musical scales based on a given tonic, octave, and scale type. It simplifies the process of obtaining notes in the correct pitch for various scales, facilitating musical application development.

Features

• Generate Scales: Easily retrieve scales based on the tonic, octave, and desired scale type.
• TypeScript Support: Built with TypeScript for type-safety and developer experience.
• Expandable: Developers can extend and add more scales as needed.
• Streamlined and Lightweight: Lean design without excess, clocking in at just 13.3kB unpacked size.

Installation

Using npm:

npm install leiter

Usage

Here's a simple example:

import { generateScale } from 'leiter';

const scale = generateScale('A', 4, 'major');
console.log(scale);  // ['A4', 'B4', 'C#5', 'D5', 'E5', 'F#5', 'G#5', 'A5']

API

generateScale(tonic: string, octave: number, scaleName: ScaleName): string[]

Parameters:

• tonic (NoteType): The root or starting note of the scale. It should be one of the standard note names (e.g., "C", "D#"). Please note that flat notes are note supported in the current release. Instead use the aquavalent sharp note.
• octave (Octave): The octave in which the scale is to be generated. Represented as numbers between 0 - 8, where "C4" is the Middle C.
• scaleName (ScaleType): The name of the scale pattern you want to generate. The library supports a vast array of scales, from standard major and minor scales to unique scales from diverse global traditions.

Returns:

An array of string values, each representing a note with it's pitch in the generated scale.

Types

ScaleType

type ScaleType = "major" | "minor" | "harmonicMinor" | "melodicMinor" | "pentatonicMajor" | "pentatonicMinor" | "bluesMinor" | "bluesMajor" | "phrygian" | "locrian" | "dorian" | "mixolydian" | "lydian" | "wholeTone" | "diminishedWholeHalf" | "diminishedHalfWhole" | "augmented" | "doubleHarmonic" | "hungarianGypsy" | "hungarianMinor" | "neapolitanMinor" | "neapolitanMajor" | "persian" | "romanianMinor" | "hirajoshi" | "inSen" | "iwato" | "kumoi" | "slendro" | "pelog" | "chineseMajor" | "chineseMinor" | "ragaBhairavi" | "ragaKafi" | "balinese";

NoteType

export type NoteType = "C" | "C#" | "D" | "D#" | "E"  | "F"  | "F#" | "G"  | "G#" | "A"  | "A#" | "B";

Octave

export type Octave = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8;

Supported Scales

| Scale Name | Formula | Description | |----------------------|---------------------------------------------|----------------------------------------| | Major | 2, 2, 1, 2, 2, 2, 1 | Bright, happy sound; commonly used in Western music | | Minor | 2, 1, 2, 2, 1, 2, 2 | Sad, more emotional tone compared to major | | Harmonic Minor | 2, 1, 2, 2, 1, 3, 1 | Combines elements of minor and middle-eastern music; characterized by a raised seventh note | | Melodic Minor | 2, 1, 2, 2, 2, 2, 1 | Traditionally, raises the sixth and seventh notes when ascending and follows the natural minor when descending. | | Pentatonic Major | 2, 2, 3, 2, 3 | Five-note scale; foundational to blues music | | Pentatonic Minor | 3, 2, 2, 3, 2 | Five-note scale; foundational to blues music | | Blues Minor | 3, 2, 1, 1, 3, 2 | Used in blues music; conveys feelings of melancholy | | Blues Major | 2, 1, 1, 3, 2, 3 | Brighter blues sound | | Phrygian | 1, 2, 2, 2, 1, 2, 2 | Dark, Spanish flavor; starts on the third degree of the major scale | | Locrian | 1, 2, 2, 1, 2, 2, 2 | Unsettled, dissonant; starts on the seventh degree of the major scale | | Dorian | 2, 1, 2, 2, 2, 1, 2 | Jazzy, starts on the second degree of the major scale | | Mixolydian | 2, 2, 1, 2, 2, 1, 2 | Bright, but less so than major; starts on the fifth degree of the major scale | | Lydian | 2, 2, 2, 1, 2, 2, 1 | Dreamy, starts on the fourth degree of the major scale | | Whole Tone | 2, 2, 2, 2, 2, 2 | Dreamlike, lacking tonal center; all whole steps | | Diminished Whole Half| 2, 1, 2, 1, 2, 1, 2, 1 | Symmetrical; creates tension and suspense | | Diminished Half Whole| 1, 2, 1, 2, 1, 2, 1, 2 | Alternate form of diminished scale; intense dissonance | | Augmented | 3, 1, 3, 1, 3 | Bright, raised pattern; every other note is augmented | | Double Harmonic | 1, 3, 1, 2, 1, 3, 1 | Exotic, Middle Eastern and Gypsy flavor | | Hungarian Gypsy | 2, 1, 3, 1, 1, 2, 1 | Similar to harmonic minor with augmented fourth | | Hungarian Minor | 2, 1, 3, 1, 1, 3, 1 | Variant of harmonic minor with augmented fourth | | Neapolitan Minor | 1, 2, 2, 2, 1, 3, 1 | Mix of Phrygian and harmonic minor | | Neapolitan Major | 1, 2, 2, 2, 2, 2, 1 | Brighter variant of Neapolitan Minor | | Persian | 1, 3, 1, 1, 2, 3, 1 | Middle Eastern flavor; combines Phrygian dominant and Locrian | | Romanian Minor | 2, 1, 3, 1, 2, 1, 2 | Gypsy flavor; mix of Dorian and Phrygian | | Hirajoshi | 2, 1, 4, 1, 4 | Associated with Japanese Koto music | | In Sen | 1, 4, 2, 3, 2 | Traditional Japanese scale | | Iwato | 1, 4, 1, 4, 2 | Pentatonic scale used in Japanese court music | | Kumoi | 2, 1, 4, 2, 3 | Another scale from Japanese Koto music | | Slendro | 2, 2, 2, 2, 4 | Pentatonic scale found in Java and Bali | | Pelog | 1, 2, 4, 1, 4 | Another scale from the gamelan music of Java and Bali | | Chinese Major | 4, 2, 1, 1, 4 | Traditional Chinese pentatonic scale | | Chinese Minor | 3, 2, 3, 2, 2 | Another version of a Chinese pentatonic scale | | Raga Bhairavi | 1, 2, 2, 1, 2, 1, 3 | A morning raga | | Raga Kafi | 2, 1, 2, 2, 2, 1, 2 | Evening raga with similarities to the Dorian mode | | Balinese | 1, 3, 2, 4, 2 | Associated with Balinese gamelan music |

To Do:

• [ ] Add support for flat notes as tonic