A webpack helper to find dependencies of your project that require transpilation with Babel (and @babel/preset-env
)
by comparing your minimum Node.js engine against theirs (engines
in package.json
), and/or by determining
their minimum Node.js engine or published
ES2015/ES6+ source (module
/jsnext:main
in package.json
)
to require features provided by plugins and polyfills from @babel/preset-env
.
This mainly aims to solve errors during minification in production builds, since some ES2015+ features like arrow functions
are unsupported by the
native UglifyJS webpack plugin through at least 3.x
.
See issues below for examples of this error and affected modules.
Update: Webpack now uses Terser rather than Uglify for minification - this example may no longer be valid.
This module generates regular expressions to be used in the exclude
or include
properties
of your babel-loader
rule in your configuration.
Use
import babelEnvDeps from 'webpack-babel-env-deps'
export default {
module: {
rules: [
{
test: /\.js$/,
exclude: [
babelEnvDeps.exclude() // returns /node_modules(?!(/|\\)(detect-indent|request|...)(/|\\))/
],
use: {
loader: 'babel-loader',
// specify options here or in `.babelrc`
options: {
presets: [
[
'env',
{
targets: {
browsers: ['> 1%, last 2 versions, Firefox ESR'],
uglify: true
}
}
]
]
}
}
}
]
}
}
Options
Functions exclude
amd include
accept an optional options
object with following properties:
mainFields
?array | ?boolean
Optional. This should match your resolve.mainFields
if you specify it in your webpack config, else it assumes the default of ['browser', 'module', 'main']
.
This is used to determine modules published with ES2015+ module support as module
/jsnext:main
,
which by default webpack will load in preference to main
, so that its
engines
field might reflect main
support rather than module
/jsnext:main
support,
so we must assume we must transpile the module
/jsnext:main
version.
If you want to disable module
/jsnext:main
detection, and rely only on engines
,
you can set mainFields
to false
explicitly.
This would assume all dependencies with a module
/jsnext:main
field point to a graph of files that are fully transpiled down
to code that can run in environments indicated by engines
,
other than retaining ES modules syntax (for tree-shaking or other purposes).
This was the goal of the module
field according to Rollup,
but the jsnext:main
field could have ambiguities (see this write-up),
and package authors in the wild may not always respect these conventions,
so caveat emptor!
except
?array | ?string | ?function
Optional. This adds exceptions to the inclusion or exclusion rules.
For example, include({ except: ['foo'] })
will prevent foo
from being
included for transpilation even if it would normally meet the criteria.
And exclude({ except: ['foo'] })
will include foo
for transpilation
even if it doesn’t otherwise meet transpilation criteria.
engines
?object | ?boolean
Optional. This optionally overrides the engines
key in your package.json
.
Or set to false
to suppress any use of your engines
for determining dependencies to transpile.
defaultEngines
?object | ?boolean
Optional. Default is false
.
This optionally provides the engines
key when missing from any dependencies.
For example, exclude({ defaultEngines: { 'node': '>= 4' } })
will assume that
dependencies without engines
require node 4, and determine transpilation normally.
Or set to true
to enable transpilation for dependencies without enough information.
For example, exclude({ defaultEngines: true })
.
Issues
- https://github.com/webpack/webpack/issues/2031
- https://github.com/webpack/webpack/issues/2031#issuecomment-315797985
- https://github.com/webpack/webpack/issues/4296
- https://github.com/babel/babel-loader/issues/171
- https://github.com/sindresorhus/strip-indent/issues/1
- https://github.com/sindresorhus/pretty-bytes/issues/31
- https://github.com/sindresorhus/ama/issues/446
- https://github.com/caolan/async/issues/1351
Reference
- https://github.com/facebookincubator/create-react-app/issues/1125#issuecomment-264217076
- https://webpack.js.org/configuration/resolve/#resolve-mainfields
- http://2ality.com/2017/07/npm-packages-via-babel.html
- http://2ality.com/2017/06/pkg-esnext.html
- https://github.com/SamVerschueren/babel-engine-plugin