pitchpipe.js

$(document).ready(function() {
   var AudioContext = window.AudioContext || window.webkitAudioContext;
   var audioContext = new AudioContext();
   var frequencies = {
	f_low: 349.23, 
	f_sharp: 369.99, 
	g: 392.00, 
	g_sharp: 415.30, 
	a: 440.00, 
	a_sharp: 466.16, 
	b: 493.88, 
	c: 523.25, 
	c_sharp: 554.37, 
	d: 587.33, 
	d_sharp: 622.25, 
	e: 659.25, 
	f_high: 698.46};
	
   var currOscillator;
   
   var playNote = function playNote(freq, duration, waveform) {
	 if (currOscillator) {
	   currOscillator.stop(0);
	 }
     var osc = audioContext.createOscillator();
	 osc.frequency.value = freq;
	 osc.type = waveform;
	 osc.connect(audioContext.destination);
	 osc.start(0);
	 setTimeout(function() { 
	   osc.stop(0); 
	   currOscillator = undefined; 
	 }, duration);
	 currOscillator = osc;
   }
   
   $("button.noteButton").click(function() {
     var noteId = $(this).data('noteId');
	 var duration = $("select#duration").val();
	 var baselineFreq = $('select[name="baselineFreq"]').val();
	 var waveform = $('select[name="waveform"]').val();
	 playNote(frequencies[noteId] * baselineFreq/440, duration * 1000, waveform);
   })
});