Accepted answer

Generally, you need to include the specified polyfills for ES5 features (as you've noticed):

You may also need HTML5 Shiv in addition to the the polyfills you've provided.

More specifically, though, the problem is probably not with polyfills but with the document mode IE9 is running in. You want to make sure that you are setting the correct document mode in your HTML file so IE knows which version to target. Otherwise, even though you are using IE9 it may be targeting IE7 which is no good.

<meta http-equiv="X-UA-Compatible" content="IE=edge">


In index.js file you have to add polyfill. These imports should be in the first of your import.

import 'react-app-polyfill/ie9';
import 'react-app-polyfill/ie11';   
//other imports

Now open in ur ie it works.

Before import you have to install react-app-polyfill.

 //To install use below command:

 npm install react-app-polyfill

link reference:

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