dspjs/test/fft-test.js

DSP.js is a comprehensive digital signal processing library for javascript

load('audio-harness.js');
load('dsp.js');

var iterations = 100;
var fft = new FFT(frameBufferLength / channels, rate);

var calcFFT = function() {
  var fb     = getFramebuffer(),
      signal = DSP.getChannel(DSP.MIX, fb);

  fft.forward(signal);
};

runTest(calcFFT, iterations);