Display current React version

Usually you know what version of React your app is using by opening the package.json, or poking around in node_modules/react/index.js. But perhaps there are many packaging abstractions in between your command line and the server. Especially if you have a continous integration server that builds your static assets and if that CI uses caching. It might get scary.

If you really want to print out what version of React is rendering your app here's one way to do that:

import React from 'react'

class Introspection extends React.Component {
  render() {
    return <div>
      Currently using React {React.version}
    </div>
  }
}

Suppose that you want this display to depend on the app being in dev or prod mode:

import React from 'react'

class Introspection extends React.Component {
  render() {
    return <div>
      {
        process.env.NODE_ENV === 'development' ?
        <p>Currently using React {React.version}</p> : null
      }
    </div>
  }
}

Note that there's no need to import process.

See this CodeSandbox snippet for a live example.