Module not found: Error: Can't resolve 'core-js/es6'

Question

I\'ve got a problem with my build process in relation to my React app.

I always get the following error:

Module not found: Error: Can\'t resolve \'co

Answer 1

Ended up to have a file named polyfill.js in projectpath\src\polyfill.js That file only contains this line: import 'core-js'; this polyfills not only es-6, but is the correct way to use core-js since version 3.0.0.

I added the polyfill.js to my webpack-file entry attribute like this:

entry: ['./src/main.scss', './src/polyfill.js', './src/main.jsx']

Works perfectly.

I also found some more information here : https://github.com/zloirock/core-js/issues/184

The library author (zloirock) claims:

ES6 changes behaviour almost all features added in ES5, so core-js/es6 entry point includes almost all of them. Also, as you wrote, it's required for fixing broken browser implementations.

(Quotation https://github.com/zloirock/core-js/issues/184 from zloirock)

So I think import 'core-js'; is just fine.

Answer 2

Change all "es6" and "es7" to "es" in your polyfills.ts and polyfills.ts (Optional).

• From: import 'core-js/es6/symbol';
• To: import 'core-js/es/symbol';

Answer 3

Just change "target": "es2015" to "target": "es5" in your tsconfig.json.

Work for me with Angular 8.2.XX

Tested on IE11 and Edge

Answer 4

After Migrated to Angular8, core-js/es6 or core-js/es7 Will not work.

You have to simply replace import core-js/es/

For ex.

import 'core-js/es6/symbol'  

to

import 'core-js/es/symbol'

This will work properly.

Answer 5

Sure, I had a similar issue and a simple

npm uninstall @babel/polyfill --save &&
npm install @babel/polyfill --save

did the trick for me.

However, usage of @babel/polyfill is deprecated (according to this comment) so only try this if you think you have older packages installed or if all else fails.

Answer 6

I found possible answer. You have core-js version 3.0, and this version doesn't have separate folders for ES6 and ES7; that's why the application cannot find correct paths.

To resolve this error, you can downgrade the core-js version to 2.5.7. This version produces correct catalogs structure, with separate ES6 and ES7 folders.

To downgrade the version, simply run:

npm i -S core-js@2.5.7

In my case, with Angular, this works ok.