Usage

Edit src/components/ChargifyForm.js and fill in your own data under publicKey and serverHost in the first useEffect function call.

Next run:

npm install
npm start

Explanation for switching off eslint warnings

On line 44 of src/components/ChargifyForm.js: We're fine because we really only want this hook to run once when the component is mounted.
On line 53 of src/components/ChargifyForm.js: We're also fine because chargify.current does not point to a node rendered by React.

https://reactjs.org/docs/hooks-reference.html
https://stackoverflow.com/questions/53464595/how-to-use-componentwillmount-in-react-hooks