Pitch class calculator

pitch_class.js

var sharpLabels = ["A", "A♯", "B", "C", "C♯", "D", "D♯", "E", "F", "F♯", "G", "G♯"];
var flatLabels = ["A", "B♭", "B", "C", "D♭", "D", "E♭", "E", "F", "G♭", "G", "A♭"];

function pitchClass(freq_Hz, labels) {
    var cents = Math.round(1200 * Math.log(freq_Hz/440) / Math.log(2));
    var semitones = Math.round(cents / 100);

    var pclass = (((semitones % 12) + 12) % 12);
    var octave = 4 + Math.floor(semitones / 12);
    var tuning = cents - semitones * 100;

    return {
        pitch_class: labels[pclass],
        octave: octave,
        tuning_cents: tuning
    };
}