A simple way to handle showing modals with react-router version 4.
Install using yarn or npm.
npm install modal-react-router --save
yarn add modal-react-router
You will also need to install some other modules as peers.
TBH, if you are looking at this package you probably already have these, but you might want to check for version compatibility.
react-router-dom version 4
react, version 15 or higher
yarn add react-router-dom react react-dom.