Babel-loader: Can not compile code under the node_modules

[kogai]

I'm submitting a bug report

Webpack Version:
4.25.1

Babel Core Version:
7.1.5

Babel Loader Version:
8.0.4

Please tell us about your environment:
MacOS 10.13.6

Current behavior:

I want to compile codes through the babel also exists under the node_modules.

Expected/desired behavior:

The bebel compiles codes under the node_modules properly, but without my own .babelrc.
(In the other word, it compiles without any presets and also plugins)

I'd created a repository which reproduces the behavior.

What is the expected behavior?

I'd expect if babel-loader compiles also code under the node_modules, those function using arrow expression might be function literal, too like here.

[kogai]

I got progress a bit, if I convert .babelrc to babel.config.js with same configuration, babel-loader worked as expected.

That's odd 🤔

[nicolo-ribaudo]

It's because .babelrc doesn't "leak" across different packages (delimited by package.json)

[xFloooo]

I also fell into this trap...

[sbrandwoo]

In previous versions of babel, webpack and babel-loader I could do the following, to transpile certain dependencies in node_modules (all our internal projects start webapp-):

{
    test: /\.js$/,
    include: {
        or: [{ not: [/node_modules/] }, /node_modules\/webapp-/],
    },
    use: ['babel-loader'],
},

This is no longer true when defining config inside .babelrc, only when config is in babel.config.js.

[zhaoyao91]

same bug here

with

"webpack": "^5.18.0",
"babel-loader": "^8.2.2",

If I use .babelrc, the files in node_modules are not compiled.

workaround is to change .babelrc to babel.config.js or set options in the webpack rule config.

[nicolo-ribaudo]

It's not a bug.

• .babelrc means "only apply this config to the specific package containing this config file"
• babel.config.js (or babel.config.json) means "apply this config to the whole project.

https://babeljs.io/docs/en/config-files