@trackr/effects-gain/lib/note-frequency.js

A subpackage of trackr that contains gain effects.

export const noteFrequency = function (note) {
    var notes = ['A', 'A#', 'B', 'C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#'], octave, keyNumber;
    if (note.length === 3) {
        octave = parseInt(note.charAt(2));
    }
    else {
        octave = parseInt(note.charAt(1));
    }
    keyNumber = notes.indexOf(note.slice(0, -1));
    if (keyNumber < 3) {
        keyNumber = keyNumber + 12 + ((octave - 1) * 12) + 1;
    }
    else {
        keyNumber = keyNumber + ((octave - 1) * 12) + 1;
    }
    // Return frequency of note
    return 440 * Math.pow(2, (keyNumber - 49) / 12);
};