jsfft

Small, efficient Javascript FFT implementation for node or the browser.

Usage

JSFFT ships with a complex_array and a fft module.

var data = new complex_array.ComplexArray(512)
// Use the in-place mapper to populate the data.
data.map(function(value, i, n) {
  value.real = (i > n/3 && i < 2*n/3) ? 1 : 0
})

Including the fft module attaches FFT methods to ComplexArray:

var frequencies = data.FFT()
// Implement a low-pass filter using the in-place mapper.
frequencies.map(function(frequency, i, n) {
  if (i > n/5 && i < 4*n/5) {
    frequency.real = 0
    frequency.imag = 0
  }
})

Alternatively, frequency-space filters can be implemented via the frequencyMap:

var filtered = data.frequencyMap(function(frequency, i, n) {
  if (i > n/5 && i < 4*n/5) {
    frequency.real = 0
    frequency.imag = 0
  }
})

Other Implementations

DSP is a full featured Digital Signal Processing library in JS which includes a JS FFT implementation.