react Transition group

# npm
npm install react-transition-group --save

# yarn
yarn add react-transition-group

/* Answer to: "react Transition group" */

/*
  Exposes simple components useful for defining entering and exiting
  transitions. React Transition Group is not an animation library
  like React-Motion, it does not animate styles by itself. Instead
  it exposes transition stages, manages classes and group elements
  and manipulates the DOM in useful ways, making the implementation
  of actual visual transitions much easier.
  
  Install it here:
  https://reactcommunity.org/react-transition-group/
*/