Add sideEffects flag

[andrewLapshov]

Hello! I need to add sideEffects: false for correct tree-shaking of Webpack (docs).

[zpao]

Please revert unnecessary changes before I can consider this.

[andrewLapshov]

Ready

[zpao]

Thanks! Ok if I'm reading this correctly, all that would change is that it would enable Webpack to remove QRCodeCanvas from your app bundle if you only used QRCodeSVG (for example)?

[andrewLapshov]

Yes, without this flag webpack will always include whole package to final bundle.

[zpao]

From what I'm reading, this marks the whole module as side effect free, but it's not quite true.

This does run on import with some module global state. Does this need to be cleaned up?

qrcode.react/src/index.tsx

Lines 169 to 181 in 15f4b93

	// For canvas we're going to switch our drawing mode based on whether or not
	// the environment supports Path2D. We only need the constructor to be
	// supported, but Edge doesn't actually support the path (string) type
	// argument. Luckily it also doesn't support the addPath() method. We can
	// treat that as the same thing.
	const SUPPORTS_PATH2D = (function () {
	try {
	new Path2D().addPath(new Path2D());
	} catch (e) {
	return false;
	}
	return true;
	})();

[andrewLapshov]

ChatGPT says you are right :)

Yes, the code below is a side effect. A side effect is a change in the state of a program or external environment that occurs as a result of executing certain code. In this case, the code performs operations to create and add a path to a Path2D object, which can change the state of the program or environment.

[zpao]

I'm up for doing that differently. It can be a fn call that caches a global so it's not a side effect. I would like to see what's actually necessary to make your change work. A quick example even with #208 applied doesn't seem to have any changes in the generated bundle. See https://github.com/zpao/qrcode.react/tree/sideEffects-test.

[kachkaev]

Hmm IDK if SUPPORTS_PATH2D counts as a side-effect TBH. It does not set anything like globalThis.foo = 42. Running it zero times or 100 times does not change anything apart from the returned value.

If SUPPORTS_PATH2D is not needed, it will be tree-shaken away. If it is needed, its value will be assigned on module load. Looks safe to use with sideEffects: false. This flag can be handy for:

• separate components in different files #188
• Support for server components #347

[zpao]

Ok I think I understand this better than I did before and it should be safe. Let's do it.