305 lines
7.2 KiB
Markdown
305 lines
7.2 KiB
Markdown
# PostCSS Media Minmax
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[](https://travis-ci.org/postcss/postcss-media-minmax)
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[](https://www.npmjs.com/package/postcss-media-minmax)
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[](https://www.npmjs.com/package/postcss-media-minmax)
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[](http://opensource.org/licenses/MIT)
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> 写简单优雅的 Media Queries！
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Media Queries 中的 `min-width` 和 `max-width` 等属性非常容易混淆，每次看到他们，我都想哭。现在[新的规范](https://drafts.csswg.org/mediaqueries/#mq-range-context)中，可以使用更加直观的 `>=`或`<=` 替代 media queries 中的 min-/max- 前缀。
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**V2.1.0 开始支持 `>` 或 `<` 符号。**
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这是一个实现 [CSS Media Queries Level 4](http://dev.w3.org/csswg/mediaqueries/) Polyfill 的插件，让你现在就可以使用这些特性，妈妈再也不用担心我记不住了，鹅妹子嘤！
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[English](README.md)
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-----
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## 安装
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$ npm install postcss-media-minmax
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## 快速开始
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示例 1：
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```js
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var fs = require('fs')
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var postcss = require('postcss')
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var minmax = require('postcss-media-minmax')
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var css = fs.readFileSync('input.css', 'utf8')
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var output = postcss()
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.use(minmax())
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.process(css)
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.css
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console.log('\n====>Output CSS:\n', output)
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```
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或者只需：
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```js
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var output = postcss(minmax())
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.process(css)
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.css
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```
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input.css：
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```css
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@media screen and (width >= 500px) and (width <= 1200px) {
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.bar {
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display: block;
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}
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}
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```
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你将得到：
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```css
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@media screen and (min-width: 500px) and (max-width: 1200px) {
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.bar {
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display: block;
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}
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}
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```
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## CSS 语法
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### [语法](http://dev.w3.org/csswg/mediaqueries/#mq-syntax)
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```
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<mf-range> = <mf-name> [ '<' | '>' ]? '='? <mf-value>
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| <mf-value> [ '<' | '>' ]? '='? <mf-name>
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| <mf-value> '<' '='? <mf-name> '<' '='? <mf-value>
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| <mf-value> '>' '='? <mf-name> '>' '='? <mf-value>
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```
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PostCSS Media Minmax 目前并没有实现 `200px >= width` 或者 `200px <= width` 这样的语法，因为这样的语法可读性并不不是太好。
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## [取值(Values)](http://dev.w3.org/csswg/mediaqueries/#values)
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**The special values:**
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* [<ratio>](http://dev.w3.org/csswg/mediaqueries/#typedef-ratio)
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<ratio> 是一个正（非零非负）的 <integer>（整型）取值，其后跟随0个或多个空白，接着跟随一个斜线（“/”），再跟随0个或多个空白，最后跟随一个正<integer>。
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```css
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@media screen and (device-aspect-ratio: 16 / 9) {
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/* rules */
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}
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/* equivalent to */
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@media screen and (device-aspect-ratio: 16/9) {
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/* rules */
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}
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```
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* [<mq-boolean>](http://dev.w3.org/csswg/mediaqueries/#typedef-mq-boolean)
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<mq-boolean> 值是一个 0 或 1 的 <integer>（整型）取值。其他任何整数无效。注意， 在 CSS 中 -0 总是等价于 0 的，所以也作为一种有效的 <mq-boolean> 取值。
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```css
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@media screen and (grid: -0) {
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/* rules */
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}
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/* equivalent to */
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@media screen and (grid: 0) {
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/* rules */
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}
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```
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## 如何使用
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### 简写
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示例 1中同一个 Media features name 同时存在 `>=` 和 `<=` 时，可以简写为：
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```css
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@media screen and (500px <= width <= 1200px) {
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.bar {
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display: block;
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}
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}
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/* 或者 */
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@media screen and (1200px >= width >= 500px) {
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.bar {
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display: block;
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}
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}
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```
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都会得到一样的输出结果：
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```css
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@media screen and (min-width: 500px) and (max-width: 1200px) {
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.bar {
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display: block;
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}
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}
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```
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**注意**：当 Media features name 在中间的时候，一定要保证两个 `<=` 或 `>=` 的方向一致，否则不会转换。
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例如在下面的示例中，width 大于等于 500px 同时又大于等于 1200px，这在语法和逻辑上都是错误的。
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```css
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@media screen and (1200px <= width >= 500px) {
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.bar {
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display: block;
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}
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}
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```
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### 支持的 Media features name
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规范中目前以下属性支持 min-/max 前缀，PostCSS Media Minmax 全部支持自动转换。
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* `width`
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* `height`
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* `device-width`
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* `device-height`
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* `aspect-ratio`
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* `device-aspect-ratio`
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* `color`
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* `color-index`
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* `monochrome`
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* `resolution`
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### 支持在 `@custom-media` 中使用 & Node Watch
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```js
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var fs = require('fs')
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var chokidar = require('chokidar')
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var postcss = require('postcss')
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var minmax = require('postcss-media-minmax')
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var customMedia = require('postcss-custom-media')
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var src = 'input.css'
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console.info('Watching…\nModify the input.css and save.')
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chokidar.watch(src, {
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ignored: /[\/\\]\./,
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persistent: true
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}).on('all',
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function(event, path, stats) {
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var css = fs.readFileSync(src, 'utf8')
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var output = postcss()
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.use(customMedia())
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.use(minmax())
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.process(css)
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.css;
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fs.writeFileSync('output.css', output)
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})
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```
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input.css:
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```css
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@custom-media --foo (width >= 20em) and (width <= 50em);
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@custom-media --bar (height >= 300px) and (height <= 600px);
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@media (--foo) and (--bar) {
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}
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```
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output.css:
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```css
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@media (min-width: 20em) and (max-width: 50em) and (min-height: 300px) and (max-height: 600px) {
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}
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```
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### Grunt
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```js
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module.exports = function(grunt) {
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grunt.initConfig({
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pkg: grunt.file.readJSON('package.json'),
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postcss: {
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options: {
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processors: [
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require('autoprefixer-core')({ browsers: ['> 0%'] }).postcss, //Other plugin
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require('postcss-media-minmax')(),
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]
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},
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dist: {
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src: ['src/*.css'],
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dest: 'build/grunt.css'
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}
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}
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});
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grunt.loadNpmTasks('grunt-contrib-uglify');
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grunt.loadNpmTasks('grunt-postcss');
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grunt.registerTask('default', ['postcss']);
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}
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```
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### Gulp
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```js
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var gulp = require('gulp');
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var rename = require('gulp-rename');
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var postcss = require('gulp-postcss');
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var selector = require('postcss-media-minmax')
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var autoprefixer = require('autoprefixer-core')
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gulp.task('default', function () {
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var processors = [
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autoprefixer({ browsers: ['> 0%'] }), //Other plugin
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minmax()
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];
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gulp.src('src/*.css')
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.pipe(postcss(processors))
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.pipe(rename('gulp.css'))
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.pipe(gulp.dest('build'))
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});
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gulp.watch('src/*.css', ['default']);
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```
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## 贡献
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* 安装相关的依赖模块。
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* 尊重编码风格（安装 [EditorConfig](http://editorconfig.org/)）。
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* 在[test](test)目录添加测试用例。
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* 运行测试。
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```
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$ git clone https://github.com/postcss/postcss-media-minmaxs.git
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$ git checkout -b patch
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$ npm install
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$ npm test
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```
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## 致谢
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* 感谢 PostCSS 作者 [Andrey Sitnik](https://github.com/ai)，带给我们如此简单易用的 CSS 语法解析工具。
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* 感谢 [Tab Atkins Jr.](http://xanthir.com/contact/) 辛苦编写了 Media Queries Level 4 规范。
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* 感谢 [@紫云飞](http://weibo.com/p/1005051708684567) 对本插件的建议和帮助。
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## [Changelog](CHANGELOG.md)
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## [License](LICENSE)
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