In most cases of core-js usage with preset-env, I see something like corejs: 3 in the config. With installed [email protected].

The first core-js@3 release was in March 2019 and since then the number of core-js features has almost doubled.

corejs: 3 in the preset-env config is interpreted [email protected] which limits the subset of used core-js features only to features that were in [email protected] and, in most cases, is not that the user expect.

I propose to limit potentially incorrect corejs option values.

• Disallow SemVer strings without a minor component, instead of corejs: "3" it should be at least corejs: "3.0"
• Disallow numbers: even if someone writes corejs: 3.30 it will be interpreted as corejs: 3.3

From @JLHwung:

What about we also offer two magic options in Babel 8?

• corejs: "node_modules": use whatever version in ./node_modules/core-js/package.json
  This is for the people who bundle core-js with their website
• corejs: "package.json": use the minimum version specified in packageJson.dependencies["core-js"]
  This is for library authors that specified core-js as a dependency

For more sophisticated usage, please specify your own core-js version.