fftjs

fftjs is a compact Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) library for JavaScript.
It implements the Cooley-Tukey radix-2 Decimation In Time (DIT) algorithm.

How to install

This package is available on npm.

npm install --save fftjs

How to use

The input can be either an array:
``javascript
// must be a power of 2.
let signal = [0.13, -0.45, ....];
`

Or an object consisting of a field named real
`javascript
let signal = {
'real': [0.13, -0.45, ....]
};
`

Then, you can compute the FFT like so:

`javascript
const fftjs = require('fftjs');

let phasors = fftjs.fft(signal);

console.log("phasors: " + phasors);

/*
phasors: {
real: [...],
imag: [...]
};
*/
`

phasors now contains the complex values in the ferquency domain representation of the signal!

We can also reconstruct our original time-domain signal from the complex phasors.

`javascript
let reconstructedSignal = jsfft.ifft(phasors);

console.log("reconstructed signal: " + reconstructedSignal);

/*
reconstruted signal: [0.13, -0.45, ....];

reconstructedSignal should be identical to original signal (with very slight rounding errors caused by JavaScript)
*/
``