Using p5.sound.js in instance mode: 'p5.Amplitude() not a constructor'

Question

I am using an npm, webpack, babel environment to write an application with p5.js. To be able to have the sketch as a module, I have the sketch in instance mode and import the library and add-ons as modules:

import p5 from 'p5';
import 'p5/lib/addons/p5.sound';
import 'p5/lib/addons/p5.dom';

Then I load them to the window inside my sketch:

const sketch = (p5) => {
   window.p5 = p5;
   ...
}
new p5(sketch);

When I try to use:

amp = new p5.Amplitude()

I get a 'p5.Amplitude is not a constructor' error. My prediction is that there is a conflict between naming the library p5 on the window and using the constructors from the library that use p5.something like p5.Amplitude, p5.Vector, p5.Soundfile. I have not been able to find a workaround to using these objects or constructors within instance mode. I am however able to use the methods from these objects that do not require a constructor. For example, loadSound() is a method of p5.Soundfile. The following works:

sound = p5.loadSound('assets/sound.wav)

but when I try console.log(p5.SoundFile) I get undefined.

I am lost!

Answer 1

I'm not a JavaScript expert, but your syntax doesn't match the syntax on the instance mode page.

Specifically, what are you doing here?

const sketch = (p5) => {
   window.p5 = p5;
   ...
}
new p5(sketch);

Compare that to the syntax on the instance mode page:

var sketch = function (p) {
  var gray = 0; 

  p.setup = function () {
    p.createCanvas(600, 400);
  };

  p.draw = function () {
    p.background(gray);
    p.rect(p.width/2, p.height/2, 200, 200);
  };

  p.mousePressed = function () {
    gray = (gray + 16) % 256;
  };
};

new p5(sketch);

It looks like your code is redefining the p5 variable, which is going to cause the kinds of problems you're seeing. I would rewrite your code to no longer redefine the p5 variable, and use the syntax from the instance mode page instead:

var sketch = function(p) {
   //your code here
   //but don't change the p5 variable!
}
new p5(sketch);

Answer 2

You're correct that you're overwriting the p5 class provided by the library with the instance that's provided to your code upon construction.

This should work:

import p5 from 'p5';
import 'p5/lib/addons/p5.sound';

const sketch = (p5) => {
   window.myp5 = p5;

   p5.setup = () => {
     //whatever
   };

   p5.draw = draw;
}

function draw() {
  //methods hang off the instance:
  const mysound = myp5.loadSound("/path/to/sound.mp3");
  //constructors hang off the class:
  const amp = new p5.Amplitude()
}
new p5(sketch);

Note that myp5 is available to the draw function because of the assignment at the beginning of the sketch function. Also note that you shouldn't need to import the addons.