@typhonjs-build-test/rollup-plugin-pkg-imports
v0.5.0
Published
Provides Rollup plugins that resolve import specifiers defined in `package.json` that link other NPM packages.
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Provides three Rollup plugins that resolve import specifiers defined in package.json
imports that link other NPM packages.
importsLocal
- Resolves import specifiers as local packages w/ fully qualified sub-path exports. In this case import specifier should exactly match an actual local main package name / export.importsExternal
- Resolves NPM packages from import specifiers substituting the fully qualified name in addition to adding a regular expression to the Rollup external configuration.importsResolve
- Resolves NPM package paths to the associated import specifier.
Overview
These plugins are useful for library authors and general developers for a variety of use cases. importsExternal
in particular is helpful
when developing packages that have peer dependencies that are not directly bundled into the library package or
dependencies between sub-path exports. The plugins are similar to @rollup/plugin-node-resolve
and function as a
resolution source to resolve internal imports from package.json
.
importsExternal
automatically constructs regular expressions added to the Rollup external
configuration array in addition to resolving against the value provided for each activated imports
entry. You may use
globs in defining the imports
entries allowing targeting of external peer dependency packages that have sub-path
exports.
importsLocal
automatically constructs regular expressions added to the Rollup external
configuration array for all values that have a local path starting with ./
. Any usage of the imports
entries will be
resolved dropping the leading #
and should match the actual exports of the package. importsLocal
works best for
Typescript oriented packages in terms of generating types.
By default, for importsExternal
and importsResolve
all imports
entries that refer to a local path starting
with ./
are ignored. importsLocal
will register keys that have values that start with ./
signifying a local
path.
You may use importsExternal
and importsResolve
together, but usage of importsLocal
should be exclusive and
not paired with the former plugins without careful consideration as they serve different purposes.
Examples importsLocal
:
Example #1 package.json
imports
entry:
{
"name": "my-package",
"imports": {
"#my-package": "./src/index.ts",
"#my-package/sub": "./src/sub/index.ts"
},
"exports": {
".": {
"types": "./dist/index.d.ts",
"import": "./dist/index.js"
},
"./sub": {
"types": "/dist/sub/index.d.ts",
"import": "/dist/sub/index.js"
}
}
}
Above the main package #my-package
refers to the source code of the main export and #my-package/sub
refers to the
source code of the sub-path export my-package/sub
. When developing a local package split across independent sub-path
exports you are able to reference the local packages with the import specifier and importsLocal
will replace it
by dropping the leading #
character. When bundling each import specifier will be marked as external and not included
in the respective bundles of the main or sub-path exports.
Examples importsExternal
:
Example #1 package.json
imports
entry:
{
"imports": {
"#shortname/*": "@my-org-name/a-long-package-name/*"
},
"peerDependencies": {
"@my-org-name/a-long-package-name": ">=1.0.0"
}
}
Above the #shortname/*
is a shortened import key for @my-org-name/a-long-package-name
. You can abbreviate the keys
however you like. This allows the use of import { thing } from '#shortname/thing';
rather than the fully qualified
name: import { thing } from '@my-org-name/a-long-package-name/thing';
.
Variation on Example #1:
When developing a package with sub-path exports where there are cross-linked dependencies between various sub-path
exports you can map an import specifier to the local package. When independently bundling each sub-path export
importsExternal
will automatically handle creating the appropriate Rollup
external configuration to exclude bundling cross-linked sub-path
exports together.
Example Rollup configuration object
// Both of the following packages are optional.
import resolve from '@rollup/plugin-node-resolve';
import { generateDTS } from '@typhonjs-build-test/esm-d-ts';
import { importsExternal } from '@typhonjs-build-test/rollup-plugin-pkg-imports';
const rollupConfig = {
input: 'src/index.js',
output: {
file: 'dist/index.js',
format: 'esm'
},
plugins: [
importsExternal(),
resolve(), // Use `importsExternal` before `@rollup/plugin-node-resolve`.
generateDTS.plugin() // Optional use of `@typhonjs-build-test/esm-d-ts`.
]
}
By default the closest package.json
from the Rollup configuration input source is automatically loaded and all
imports
are processed as external.
You may provide a configuration object to importsExternal
with the following entries:
| Attribute | Type | Description |
|-----------|------|------------------------------------------|
|importsKeys
| string[] | Only target the provided imports
keys. |
| packageObj
| object | A specific package.json
object to use. |
Usage inside a ESM JS source file (./src/index.js
):
import { something } from '#shortname/sub-path';
#shortname/sub-path
is connected to @my-external-package/a-long-package-name/sub-path
and is not included in the
bundled output.
Example importsResolve
:
Example #2 package.json
imports
entry:
{
"imports": {
"#shortname/*": "@my-org-name/a-long-package-name/*"
}
}
Above the #shortname/*
is a shortened import key for @my-org-name/a-long-package-name
. You can abbreviate the keys
however you like. This allows the use of import { thing } from '#shortname/thing';
rather than the fully qualified
name: import { thing } from '@my-org-name/a-long-package-name/thing';
.
Essentially, importsResolve
is a convenience mechanism when using Rollup to automatically resolve import specifiers.
The referenced packages are included in the bundle generated without having to manually configure
@rollup/plugin-replace
or @rollup/plugin-alias
.
Additionally, you may provide a string array exportConditions
in the plugin options to resolve specific export
conditions. The default is ['node', 'import', 'default']
.
For instance if you are using Vite 4.2+
import specifiers are automatically resolved in production / Rollup builds.
This plugin functions in a similar manner, but handy for direct Rollup builds.
Synergies
If you are working on ES Modules / modern Javascript and document your code with JSDoc a great optional Rollup plugin
and tool to use is @typhonjs-build-test/esm-d-ts.
The Rollup plugin for esm-d-ts
automatically creates bundled TS declarations from ESM source and is aware of
rollup-plugin-pkg-imports
allowing the generated TS declarations to include the correct mapped packages.
Roadmap / TODO
- Evaluate any concerns for mono-repo use cases.
- Create a comprehensive testsuite; rest assured though as these plugins are used in production environments.