179 lines
4.8 KiB
Markdown
179 lines
4.8 KiB
Markdown
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# PostCSS Custom Media [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS" width="90" height="90" align="right">][postcss]
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[![NPM Version][npm-img]][npm-url]
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[![CSS Standard Status][css-img]][css-url]
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[![Build Status][cli-img]][cli-url]
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[![Support Chat][git-img]][git-url]
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[PostCSS Custom Media] lets you use Custom Media Queries in CSS, following the
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[CSS Media Queries] specification.
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```pcss
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@custom-media --small-viewport (max-width: 30em);
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@media (--small-viewport) {
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/* styles for small viewport */
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}
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/* becomes */
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@media (max-width: 30em) {
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/* styles for small viewport */
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}
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```
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## Usage
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Add [PostCSS Custom Media] to your project:
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```bash
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npm install postcss-custom-media --save-dev
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```
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Use [PostCSS Custom Media] to process your CSS:
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```js
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const postcssCustomMedia = require('postcss-custom-media');
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postcssCustomMedia.process(YOUR_CSS /*, processOptions, pluginOptions */);
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```
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Or use it as a [PostCSS] plugin:
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```js
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const postcss = require('postcss');
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const postcssCustomMedia = require('postcss-custom-media');
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postcss([
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postcssCustomMedia(/* pluginOptions */)
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]).process(YOUR_CSS /*, processOptions */);
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```
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[PostCSS Custom Media] runs in all Node environments, with special instructions for:
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| [Node](INSTALL.md#node) | [PostCSS CLI](INSTALL.md#postcss-cli) | [Webpack](INSTALL.md#webpack) | [Create React App](INSTALL.md#create-react-app) | [Gulp](INSTALL.md#gulp) | [Grunt](INSTALL.md#grunt) |
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| --- | --- | --- | --- | --- | --- |
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## Options
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### preserve
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The `preserve` option determines whether custom media and atrules using custom
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media should be preserved in their original form.
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```pcss
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@custom-media --small-viewport (max-width: 30em);
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@media (--small-viewport) {
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/* styles for small viewport */
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}
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/* becomes */
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@custom-media --small-viewport (max-width: 30em);
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@media (max-width: 30em) {
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/* styles for small viewport */
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}
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@media (--small-viewport) {
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/* styles for small viewport */
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}
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```
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### importFrom
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The `importFrom` option specifies sources where custom media can be imported
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from, which might be CSS, JS, and JSON files, functions, and directly passed
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objects.
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```js
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postcssCustomMedia({
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importFrom: 'path/to/file.css' // => @custom-selector --small-viewport (max-width: 30em);
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});
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```
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```pcss
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@media (max-width: 30em) {
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/* styles for small viewport */
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}
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@media (--small-viewport) {
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/* styles for small viewport */
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}
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```
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Multiple sources can be passed into this option, and they will be parsed in the
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order they are received. JavaScript files, JSON files, functions, and objects
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will need to namespace custom media using the `customMedia` or
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`custom-media` key.
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```js
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postcssCustomMedia({
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importFrom: [
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'path/to/file.css',
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'and/then/this.js',
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'and/then/that.json',
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{
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customMedia: { '--small-viewport': '(max-width: 30em)' }
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},
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() => {
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const customMedia = { '--small-viewport': '(max-width: 30em)' };
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return { customMedia };
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}
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]
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});
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```
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### exportTo
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The `exportTo` option specifies destinations where custom media can be exported
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to, which might be CSS, JS, and JSON files, functions, and directly passed
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objects.
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```js
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postcssCustomMedia({
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exportTo: 'path/to/file.css' // @custom-media --small-viewport (max-width: 30em);
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});
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```
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Multiple destinations can be passed into this option, and they will be parsed
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in the order they are received. JavaScript files, JSON files, and objects will
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need to namespace custom media using the `customMedia` or
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`custom-media` key.
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```js
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const cachedObject = { customMedia: {} };
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postcssCustomMedia({
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exportTo: [
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'path/to/file.css', // @custom-media --small-viewport (max-width: 30em);
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'and/then/this.js', // module.exports = { customMedia: { '--small-viewport': '(max-width: 30em)' } }
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'and/then/this.mjs', // export const customMedia = { '--small-viewport': '(max-width: 30em)' } }
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'and/then/that.json', // { "custom-media": { "--small-viewport": "(max-width: 30em)" } }
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cachedObject,
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customMedia => {
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customMedia // { '--small-viewport': '(max-width: 30em)' }
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}
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]
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});
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```
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See example exports written to [CSS](test/export-media.css),
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[JS](test/export-media.js), [MJS](test/export-media.mjs), and
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[JSON](test/export-media.json).
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[cli-img]: https://img.shields.io/travis/postcss/postcss-custom-media/master.svg
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[cli-url]: https://travis-ci.org/postcss/postcss-custom-media
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[css-img]: https://cssdb.org/badge/custom-media-queries.svg
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[css-url]: https://cssdb.org/#custom-media-queries
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[git-img]: https://img.shields.io/badge/support-chat-blue.svg
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[git-url]: https://gitter.im/postcss/postcss
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[npm-img]: https://img.shields.io/npm/v/postcss-custom-media.svg
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[npm-url]: https://www.npmjs.com/package/postcss-custom-media
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[CSS Media Queries]: https://drafts.csswg.org/mediaqueries-5/#custom-mq
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[PostCSS]: https://github.com/postcss/postcss
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[PostCSS Custom Media]: https://github.com/postcss/postcss-custom-media
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