React App converting JS to ES5 to target IE 11

Question

I currently have a react app which is not running / rendering in IE, I think due to an ES5 / ES6 problem.

The error I get is this: Syntax error.

On the line highlighted below.

    if(process.env.NODE_ENV == 'production') {
=>       module.exports = require('./cjs/react.production.min.js');
    } else {
      module.exports = require('./cjs/react.development.js');

At the top of index.js prior to compilation:

import 'babel-polyfill'; 
import 'react-app-polyfill/ie11';
import 'react-app-polyfill/stable';

package.json:

{
  "name": "reactapp",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@babel/polyfill": "^7.8.3",
    "@material-ui/core": "^3.9.3",
    "@material-ui/icons": "^3.0.2",
    "@sentry/browser": "^5.10.2",
    "adblockdetect": "0.0.2",
    "animatewithsass": "^3.2.1",
    "axios": "^0.18.1",
    "babel-polyfill": "^6.26.0",
    "core-js": "^3.6.5",
    "date-fns": "^2.10.0",
    "detectrtc": "^1.4.0",
    "easy-peasy": "^3.2.0",
    "formik": "^2.0.3",
    "google-map-react": "^1.1.5",
    "js-cookie": "^2.2.1",
    "lodash": "^4.17.15",
    "material-design-icons": "^3.0.1",
    "material-icons": "^0.3.1",
    "node-sass": "^4.13.0",
    "platform": "^1.3.5",
    "query-string": "^6.10.1",
    "react": "^16.11.0",
    "react-albus": "^2.0.0",
    "react-app-polyfill": "^1.0.6",
    "react-color": "^2.18.0",
    "react-confirm-alert": "^2.4.1",
    "react-dom": "^16.11.0",
    "react-dropzone": "^11.1.0",
    "react-loader-spinner": "^3.1.5",
    "react-media-recorder": "^1.2.0",
    "react-paginate": "^6.3.2",
    "react-router-dom": "^5.1.2",
    "react-rtc-real": "^1.11.22",
    "react-scripts": "2.1.8",
    "react-select": "^3.1.0",
    "react-simple-line-icons": "^1.0.8",
    "react-spring": "^8.0.27",
    "react-stripe-elements": "^5.1.0",
    "react-stripe-script-loader": "^1.0.16",
    "react-switch": "^5.0.1",
    "react-toastify": "^5.4.0",
    "react-toggle": "^4.1.1",
    "react-tooltip": "^3.11.2",
    "regenerator-runtime": "^0.13.5",
    "semantic-ui-css": "^2.4.1",
    "semantic-ui-react": "^0.88.2",
    "styled-components": "^4.4.1",
    "sweetalert2-react": "^0.8.3",
    "videojs": "^1.0.0",
    "videojs-record": "^4.0.0",
    "webfontloader": "^1.6.28",
    "webrtc-adapter": "^7.5.1",
    "yup": "^0.27.0"
  },
  "scripts": {
    "start": "react-app-rewired start",
    "build": "set NODE_ENV=production && react-app-rewired build",
    "test": "react-app-rewired test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all",
      "IE 11"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version",
      "IE 11"
    ]
  },
  "devDependencies": {
    "animate-sass": "^0.8.2",
    "es-check": "^5.1.1",
    "react-app-rewired": "^2.1.6"
  }
}

Inside .babelrc

{
    "presets": ["@babel/env","@babel/preset-react",["@babel/preset-env", { "targets": "defaults" }]],
    "plugins" : ["@babel/plugin-syntax-dynamic-import"]
}

Can anyone guide me in the right direction as to how to get babel to compile things properly for ES5? You'll notice here instead of ejecting, I'm using react-app-rewired, I don't think that should cause issues, so any help appreciated.

Update:

"Object doesn't support property or method 'repeat'" - when running in development mode. How do I polyfill this? I think this may be the problem.  

Answer 1

This is very similar to this Github issue in core-js

As suggested in that thread, you might add this to your preset config

 { modules: false,
   useBuiltIns: 'entry',
   corejs: 3 }

Or import the function directly

import 'core-js/features/string/repeat';

Answer 2

First In the index.js file the import is for import 'babel-polyfill'; think should be @babel/polyfill. But that would not resolve IE 11 issues.

We had a similar issue, had to switch to core-js for bundling - which you already have. But you will need @babel/core and @babel/runtime-corejs3 as dev dependencies.

Your preset needs to be changed

presets: [
             [
                 "@babel/preset-env", {
                 "useBuiltIns": "usage", 
                 corejs: { version: 3, proposals: true }
                 }
              ]
           ]

And then replace the code in index.js

 imports babel/polyfill;

with

import 'core-js/stable';

Answer 3

If you can use typescript then I'll suggest that you can transform your tsconfig.js file and change target to es5.

If not then create .babelrc file and inside it add this:

{ "presets": [ [ "@babel/preset-env", { "useBuiltIns": "entry", "forceAllTransforms": true, "corejs": "3.0.0", "targets": { "ie": "11" } } ] ] }