FFT calculation in Javascript of vibration data

  dft, fft, javascript, signal-processing

Question:- I have to calculate the FFT of time series data.

Time series data of what ?
I have a Vibration sensor that is giving me the data of displacement in x and y coordinate.

What are the Problems? I can’t find a proper library to work although I found some but I don’t know if it is working fine or not.
As far as I know, we need Sample Rate and FFTsize(number of elements) to calculate the FFT

I used the library https://www.npmjs.com/package/fft-js
in which I passed a 1D array and it returns a 2D array having some positive values and some negative values.

Question I have

  1. How does it calculate FFT without the sampling rate as far as I know a sampling rate is needed
  2. For calculating FFT does data frequency need to be constant as like idealy I am having 170 data per second but sometime if goes down as 165 and 160
  3. What are ways I can verify my fft

Ps:- I am trying to plot fft in realtime

help or resource are much appreciated as I Can’t find any resource of fft in javascript

Source: Ask Javascript Questions