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  core-js es6   if I use this in a polyfill js   import  core-js es6    That is my package json    x000D   x000D    x000D     name    test   x000D     version    1 0 0   x000D     main    index js   x000D     license    MIT   x000D     private   true  x000D     devDependencies     x000D        babel core     7 4 0   x000D        babel preset-env     7 4 2   x000D        babel preset-react     7 0 0   x000D        babel runtime     7 4 2   x000D       babel-loader     8 0 5   x000D       babel-preset-es2015     6 24 1   x000D       copy-webpack-plugin     5 0 2   x000D       css-hot-loader     1 4 4   x000D       eslint    5 15 3   x000D       eslint-config-airbnb     17 1 0   x000D       eslint-loader     2 1 2   x000D       eslint-plugin-import    2 16 0   x000D       eslint-plugin-jsx-a11y    6 2 1   x000D       eslint-plugin-react    7 12 4   x000D       file-loader     3 0 1   x000D       node-sass     4 11 0   x000D       prettier     1 16 4   x000D       react-hot-loader    4 8 0   x000D       sass-loader     7 1 0   x000D       webpack     4 29 6   x000D       webpack-cli     3 3 0   x000D       webpack-dev-server     3 2 1  x000D       x000D     dependencies     x000D       axios     0 18 0   x000D       core-js     3 0 0   x000D       prop-types     15 7 2   x000D       react     16 8 5   x000D       react-dom     16 8 5   x000D       react-redux     6 0 1   x000D       react-string-replace     0 4 1   x000D       redux     4 0 1   x000D       slick-carousel     1 8 1  x000D       x000D     scripts     x000D       dev    webpack-dev-server --hot   x000D       build    webpack --colors --profile --progress --env mode production   x000D       lint    eslint   src  --ext  js  jsx  x000D      x000D    x000D   x000D   x000D    Can someone help here

User · Answer

If you use  babel preset-env and useBuiltIns  then you just have to add corejs  3 beside the useBuiltIns option  to specify which version to use  default is corejs  2   presets              babel preset-env            useBuiltIns    usage          corejs   3                For further details see  https   github com zloirock core-js blob master docs 2019-03-19-core-js-3-babel-and-a-look-into-the-future md babelpreset-env

User · Answer

Sure  I had a similar issue and a simple  npm uninstall  babel polyfill --save  amp  amp  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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

Just change  target    es2015  to  target    es5  in your tsconfig json    Work for me with Angular 8 2 XX  Tested on IE11 and Edge

User · Answer

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

User · Answer

Change all  quot es6 quot  and  quot es7 quot  to  quot es quot  in your polyfills ts and polyfills ts

User · Answer

The imports have changed for core-js version 3 0 1 - for example   import  core-js es6 array   and  import  core-js es7 array    can now be provided simply by the following  import  core-js es array    if you would prefer not to bring in the whole of core-js

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

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