Piano-key   

Tools for working with piano keys and frequencies.



``js
var key = require('piano-key');

key.getName(49); //A4
key.getFrequency(49); //440
key.getFrequency('A4'); //440
key.getNumber('A4'); //49
key.getNumber(440); //49
key.getOctave(49); //4
key.getNote(50); //A#
key.getNote('A#4'); //A#

key.isBlack(49); //false
key.isBlack(48); //true
``