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228 lines
6.4 KiB
Markdown
228 lines
6.4 KiB
Markdown
# postcss-import
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[](https://travis-ci.org/postcss/postcss-import)
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[](https://github.com/postcss/postcss-import/blob/master/CHANGELOG.md)
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[](https://postcss.org/)
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> [PostCSS](https://github.com/postcss/postcss) plugin to transform `@import`
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rules by inlining content.
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This plugin can consume local files, node modules or web_modules.
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To resolve path of an `@import` rule, it can look into root directory
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(by default `process.cwd()`), `web_modules`, `node_modules`
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or local modules.
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_When importing a module, it will look for `index.css` or file referenced in
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`package.json` in the `style` or `main` fields._
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You can also provide manually multiples paths where to look at.
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**Notes:**
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- **This plugin should probably be used as the first plugin of your list.
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This way, other plugins will work on the AST as if there were only a single file
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to process, and will probably work as you can expect**.
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- This plugin works great with
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[postcss-url](https://github.com/postcss/postcss-url) plugin,
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which will allow you to adjust assets `url()` (or even inline them) after
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inlining imported files.
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- In order to optimize output, **this plugin will only import a file once** on
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a given scope (root, media query...).
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Tests are made from the path & the content of imported files (using a hash
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table).
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If this behavior is not what you want, look at `skipDuplicates` option
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- If you are looking for **Glob Imports**, you can use [postcss-import-ext-glob](https://github.com/dimitrinicolas/postcss-import-ext-glob) to extend postcss-import.
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- Imports which are not modified (by `options.filter` or because they are remote
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imports) are moved to the top of the output.
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- **This plugin attempts to follow the CSS `@import` spec**; `@import`
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statements must precede all other statements (besides `@charset`).
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## Installation
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```console
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$ npm install -D postcss-import
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```
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## Usage
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Unless your stylesheet is in the same place where you run postcss
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(`process.cwd()`), you will need to use `from` option to make relative imports
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work.
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```js
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// dependencies
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const fs = require("fs")
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const postcss = require("postcss")
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const atImport = require("postcss-import")
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// css to be processed
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const css = fs.readFileSync("css/input.css", "utf8")
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// process css
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postcss()
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.use(atImport())
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.process(css, {
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// `from` option is needed here
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from: "css/input.css"
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})
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.then((result) => {
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const output = result.css
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console.log(output)
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})
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```
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`css/input.css`:
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```css
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/* can consume `node_modules`, `web_modules` or local modules */
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@import "cssrecipes-defaults"; /* == @import "../node_modules/cssrecipes-defaults/index.css"; */
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@import "normalize.css"; /* == @import "../node_modules/normalize.css/normalize.css"; */
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@import "foo.css"; /* relative to css/ according to `from` option above */
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@import "bar.css" (min-width: 25em);
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body {
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background: black;
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}
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```
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will give you:
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```css
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/* ... content of ../node_modules/cssrecipes-defaults/index.css */
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/* ... content of ../node_modules/normalize.css/normalize.css */
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/* ... content of css/foo.css */
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@media (min-width: 25em) {
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/* ... content of css/bar.css */
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}
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body {
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background: black;
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}
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```
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Checkout the [tests](test) for more examples.
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### Options
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### `filter`
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Type: `Function`
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Default: `() => true`
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Only transform imports for which the test function returns `true`. Imports for
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which the test function returns `false` will be left as is. The function gets
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the path to import as an argument and should return a boolean.
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#### `root`
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Type: `String`
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Default: `process.cwd()` or _dirname of
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[the postcss `from`](https://github.com/postcss/postcss#node-source)_
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Define the root where to resolve path (eg: place where `node_modules` are).
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Should not be used that much.
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_Note: nested `@import` will additionally benefit of the relative dirname of
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imported files._
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#### `path`
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Type: `String|Array`
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Default: `[]`
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A string or an array of paths in where to look for files.
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#### `plugins`
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Type: `Array`
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Default: `undefined`
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An array of plugins to be applied on each imported files.
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#### `resolve`
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Type: `Function`
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Default: `null`
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You can provide a custom path resolver with this option. This function gets
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`(id, basedir, importOptions)` arguments and should return a path, an array of
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paths or a promise resolving to the path(s). If you do not return an absolute
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path, your path will be resolved to an absolute path using the default
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resolver.
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You can use [resolve](https://github.com/substack/node-resolve) for this.
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#### `load`
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Type: `Function`
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Default: null
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You can overwrite the default loading way by setting this option.
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This function gets `(filename, importOptions)` arguments and returns content or
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promised content.
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#### `skipDuplicates`
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Type: `Boolean`
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Default: `true`
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By default, similar files (based on the same content) are being skipped.
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It's to optimize output and skip similar files like `normalize.css` for example.
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If this behavior is not what you want, just set this option to `false` to
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disable it.
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#### `addModulesDirectories`
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Type: `Array`
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Default: `[]`
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An array of folder names to add to [Node's resolver](https://github.com/substack/node-resolve).
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Values will be appended to the default resolve directories:
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`["node_modules", "web_modules"]`.
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This option is only for adding additional directories to default resolver. If
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you provide your own resolver via the `resolve` configuration option above, then
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this value will be ignored.
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#### Example with some options
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```js
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const postcss = require("postcss")
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const atImport = require("postcss-import")
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postcss()
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.use(atImport({
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path: ["src/css"],
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}))
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.process(cssString)
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.then((result) => {
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const { css } = result
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})
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```
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## `dependency` Message Support
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`postcss-import` adds a message to `result.messages` for each `@import`. Messages are in the following format:
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```
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{
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type: 'dependency',
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file: absoluteFilePath,
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parent: fileContainingTheImport
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}
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```
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This is mainly for use by postcss runners that implement file watching.
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---
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## CONTRIBUTING
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* ⇄ Pull requests and ★ Stars are always welcome.
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* For bugs and feature requests, please create an issue.
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* Pull requests must be accompanied by passing automated tests (`$ npm test`).
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## [Changelog](CHANGELOG.md)
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## [License](LICENSE)
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