The file you probably just want to look at: form.js. This is not a package you npm install, just an example of how to handle an invisible recaptcha in react without having to npm install anything.
npm install
npm run dev
Modify form.js with your recaptcha sitekey and check the console on form submit.
There are other packages that make nice Recaptcha components, I suggest you check them out: react-recaptcha, react-google-invisible-recaptcha, and probably many more.
In an effort to fight code bloat I didn't need something that would work with n number of recaptchas within my app using random UUIDs or in vanilla JavaScript for whatever reason. So I wrote something like this and wanted to share.