Ttd_dom_ready is not defined

To fix the ‘Uncaught ReferenceError: React is not defined’ error when developing React apps, we can add the ‘react’ property to the externals property in webpack. config. json . Also, we can add import React from ‘react’; to the top of each component file to fix the error.

Most likely, you forgot to import it from the package react-dom :

The reason React and ReactDOM were split into two libraries was due to the arrival of React Native. React contains functionality utilised in web and mobile apps. ReactDOM functionality is utilised only in web apps .