Collectives™ on Stack Overflow

Find centralized, trusted content and collaborate around the technologies you use most.

Teams

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

What does this error mean? With `useBuiltIns` option, required direct setting of `corejs` option

Getting the same issue. Resolved it by installing core-js as a top level dependency and then adding it as an option to .babelrc

npm install --save core-js@3
Then updated my .babelrc file to include it as an option:
  "presets": [
    [ "@babel/preset-env", {
      "useBuiltIns": "entry",
      "corejs": 3
  "plugins": [
    "@babel/plugin-syntax-dynamic-import",
    "@babel/plugin-syntax-import-meta",
    ["@babel/plugin-proposal-class-properties", { "loose": false }],
    "@babel/plugin-proposal-json-strings"
I referenced the docs here to figure it out https://babeljs.io/docs/en/babel-preset-env#usebuiltins
                there's always a possibility of issues with major releases, of course.   Here's a blog post by one of babel's authors, written at the time of babel 7.4.0 release a few days ago, with some migration guides and info: babeljs.io/blog/2019/03/19/7.4.0#migration-from-core-js-2
– T-G
                Mar 22, 2019 at 5:54
This has been reported to parcel.js: https://github.com/parcel-bundler/parcel/issues/2819
This is due to a soft change in the newly released @babel/core 7.4 and seems to require a parcel.js change.
The solution so far is to either:
lock @babel/core to ~7.3: "@babel/core": "~7.3"
not upgrade the dependencies at all if they are locked
After reading through related discussions on github and the solutions proposed here, the following seems to be the way to go for now:
Add core-js@2 to your dependencies
npm i core-js@2
Ignore the warnings when building
When playing around with the babel config modifying targets I ran into errors either when building or when serving the project.
The documentation says "You may need to specify core-js@2 as a top level dependency in your application". https://babeljs.io/docs/en/babel-preset-env#usebuiltins
This worked for me:
npm i core-js@2
Then in babel.config.js:
  presets: [
      "@babel/env", // or others like "@vue/app"
        "useBuiltIns": "usage",
        "corejs": "core-js@2",
        // ...
You don't need to have core-js as a dependency necessarily. Just set core-js version in your babel config file (babel.config.js) @babel/env preset as follows:
  '@babel/env',
    targets: {
    corejs: 'core-js@2'
        
Thanks for contributing an answer to Stack Overflow!
Please be sure to answer the question. Provide details and share your research!
But avoid …
Asking for help, clarification, or responding to other answers.
Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.