chore: refactored from findDOMNode to refs

[tstirrat15]

Fixes #475

Description

findDOMNode is deprecated in StrictMode. It's recommended against in the official docs, and if the functionality that it enables is required, refs are a good way of addressing the problem.

This PR refactors away from findDOMNode towards refs.

Changes

• Refactor react-imgix components to use refs in favor of findDOMNode
• Refactor tests to use mount instead of shallow, since shallow doesn't create or use refs
• Remove a test function that wasn't in use

Steps to Test

See that the refactored tests are sane and passing.

Note

I wasn't quite sure what sort of work this represented (fix/feature/chore). Please let me know if a different designation is more appropriate.

[commit-lint]

Styles

• npm run pretty (fcab1a5)

Contributors

@tstirrat15, @sherwinski

[frederickfogerty]

FYI @sherwinski @jayeb this is technically a breaking change since this would break support for React <16.3 (this library currently supports React 16.0, 16.1, and 16.2). If support for these versions is desired, then callback refs can be used source.

[tstirrat15]

Good point. I can refactor towards a callback ref if that'd be preferable.

[frederickfogerty]

Thanks for the reply @tstirrat15. @sherwinski and @jayeb will reply here soon with a strategy 👍. Thanks for the PR btw 🙌

[sherwinski]

Sorry for the hold up @tstirrat15, and thanks for looking into this! I am going to err on the side of providing wider support and say that we should use callback refs here.

[tstirrat15]

Done

[sherwinski]

Awesome, thank you 🙌
I'm seeing some style changes when I run npm run pretty locally. Usually Prettier would auto fix this but it hasn't been working for some time it seems. I'm going to go ahead and commit those changes on top of what you already have and then this is good to go!

[frederickfogerty]

👏 👏 👏