React app not working in Internet Explorer 11

Question

This worked for me.

Update the development array in package.json

    "development": [
      "ie 11",
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }

Add the below code in index.js in the src folder

// These must be the first lines in src/index.js
import 'react-app-polyfill/ie11';
import 'react-app-polyfill/stable';

Then delete the node_modules folder and run

npm install

IE does not support a lot of ES6+ features by default. For more info, refer the create-react-app polyfill docs.