There are a couple relatively new tools that give you just about everything you need to build a React app in the browser.
The first is CodeSandbox. It has a couple pre-configured environments for different technologies. The main one is React. CodeSandbox describes itself as such:
an online editor that helps you create web applications, from prototype to deployment.
the friendly community where you’ll build the app of your dreams
You can quickly build and publish React apps in either of these and share them with the world.Tweet