How to set up a react-transition group?

Question

Animation

Hello. I set up a page transition without any problems by wrapping the router in a react-transition-group. But when it came to that single component (modal), I was completely stuck. We need to make sure that the CustomModal component can animate when mounting and unmounting. The documentation doesn't help. I really hope to help!
Sandbox: https://codesandbox.io/s/wn0kkoq4w7

Answer 1

https://codesandbox.io/s/yqjkoj27z1