LFO.js

A simple JavaScript library that implements LFOs in JavaScript.

What is an LFO

LFO stands for Low Frequency Oscillator - a device which oscillates between two values on a certain frequency, following a given waveform.

Note: In this library, there is no limitation concerning the frequency, as a result it can behave strangely at a high frequency

Example

Either run the example from cloning the repo, installing with npm and then running npm run example or visit http://theteapot418.github.io/LFO.js/.

Usage

Instantiation

First, import LFO:

import LFO from 'lfo-js';

or

var LFO = require('lfo-js');

To include LFO in HTML, you can:

<script src='LFO.js'></script>

and access using

window.LFO

To create an LFO, create a new instance of LFO:

const myLfo = new LFO();

The LFO class takes an object as an argument, containing these parameters:

• freq: the frequency of the oscillator
• amplitude: the amplitude of the oscillator
• waveform: string to use built in waveforms or a custom waveform function. This function takes a number between 0 and 2PI as an argument and must return a number between 0 and 1.

Example:

const myLfo = new LFO ({
  freq: 1.3,
  amplitude: 2,
  waveform(x) {
    if (x <= Math.PI) {
      return -1;
    }
    return 1;
  }
  // Same as:
  // waveform: 'square'
});

This code will create a new LFO with a frequency of 1.3Hz, an amplitude of 2 and which will produce a square signal.

Note: Every parameter is optional

Waveform functions

There are a few basic waveform functions that are included in the library.
Set waveform to one of these strings instead of a function to use it:

• sine (default value)
• triangle
• square
• sawtooth
• noise

Getting the current value

To retrieve the current value of an LFO, just use the value parameter:

const v = myLfo.value;

Changing parameters

To change parameters of an LFO, use the set function which takes the same argument as the constructor of the class:

myLfo.set({
  freq: 0.7
});