ReactJS: Uncaught ReferenceError: Set is not defined

No sure whether anyone found the right solution. However for older browser especially on Android Kitkat 4.4 browsers/webview this problem is very evident. Please use the following link for the solution

https://reactjs.org/docs/javascript-environment-requirements.html

If you are using ReactJS 16 then first include the babel-polyfill

• npm install --save babel-polyfill

Open your index.js and import the babel-polyfill

• import 'babel-polyfill'

Create a build and deploy. This should solve the issue.

I face the same issue while working on my React project. So I just install babel-polyfill package. Its working fine now.