Gatsby: WebpackError: ReferenceError: window is not defined about react-p5

[Hahlh]

Unfortunately the change doesn't seem to have worked.

Do you use build-time SSR and can successfully deploy?
I will be able to test changes to the code as soon as I am able to develop react-p5 locally 👍

[Gherciu]

@Hahlh I think a workaround on that is to just not render canvas or load p5 in SSR mode because it doesn't make sense....it doesn't affect SEO or anything else if we will not render it in SSR

[Gherciu]

because the problem here is actually with p5 itself but not with (react-p5 it just renders a

in SSR mode).....but p5 needs access to window etc.....that's why it throws errors

[Hahlh]

You would normally implement type checks in your code that prevent errors during build:

Something like:

if (typeof window !== 'undefined') {
    window.doSomething
}

In this case the error occurs directly in react-p5, meaning that I can't do anything about it without changing react-p5:

I am curious as surely other people must have it running with Gatsby?
Maybe @lambertbrady can weigh in as he proposed the first change to the window check in react-p5?

Did it work for you after the change?
Did you additionally have to wrap all the react-p5 related code in a window-checker or was wrapping those directly referring to window enough?

[Hahlh]

Update:

If I comment all react-p5 related code out, it builds again successfully. So something in my code is triggering react-p5 and it in turn fails, because window is undefined.

That should make the question to you, @lambertbrady, solved. Please excuse the unnecessary ping.

[Hahlh]

As a side note:

This is what the error logged to the terminal looks like in this case:

I am not sure whether that is something that can be improved in react-p5?

[Hahlh]

Another update:

If I leave all the code unchanged and only comment out the Sketch component return, the code builds successfully.

So that should mean, that additional window checks are required in react-p5 to prevent calls to p5, that result in a window undefined?

But it seems that p5 should also have fail-safes against this:

[Gherciu]

@Hahlh as a workaround use dinamyc imports ....just to import this library when window is available othervise no. Example.

if(window) {
const Sketch = require(react-p5)
}

[Hahlh]

@Gherciu

I hope you are doing great!

let Sketch

if (typeof window !== "undefined") {
  Sketch = require("react-p5")
}

works, although it's means mixing import and require and although the import should normally be top level?

The problem with this is, that it also somehow changes my setup, meaning where the canvas is placed etc.

Expected result:

Actual result:

I will now explore two alternative approaches from the Gatsby docs.
Customizing the webpack config to use a dummy module during build and using loadable-components.

If those don't succeed, I may try to force the setup to happen later with a useEffect, although I am not sure whether that will introduce scoping problems.

Thank you again for the fast help, @Gherciu !

[Hahlh]

In the example above, using dynamic imports as you suggested, and in using a custom webpack config, the canvas seems to get attached to the wrong parent.

In this case the absolute div on the right side.

Could I do something about that or specify precisely what the parent element should be?

---

Edit:

The current workaround I am using for attaching the canvas to the correct element, is to conditionally render not only the <SketchComp />, but all children of the main container.
This seems to work for the moment and I will now test it for deploying.