172 lines
3.1 KiB
Markdown
Executable File
172 lines
3.1 KiB
Markdown
Executable File
# postcss-calc [](https://travis-ci.org/postcss/postcss-calc)
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> [PostCSS](https://github.com/postcss/postcss) plugin to reduce `calc()`.
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This plugin reduce `calc()` references whenever it's possible.
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This can be particularly useful with the [postcss-custom-properties](https://github.com/postcss/postcss-custom-properties) plugin.
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**Note:** When multiple units are mixed together in the same expression, the `calc()` statement is left as is, to fallback to the [w3c calc() feature](http://www.w3.org/TR/css3-values/#calc).
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## Installation
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```console
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$ npm install postcss-calc
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```
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## Usage
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```js
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// dependencies
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var fs = require("fs")
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var postcss = require("postcss")
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var calc = require("postcss-calc")
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// css to be processed
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var css = fs.readFileSync("input.css", "utf8")
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// process css
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var output = postcss()
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.use(calc())
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.process(css)
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.css
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```
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**Example** (with [postcss-custom-properties](https://github.com/postcss/postcss-custom-properties) enabled as well):
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```js
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// dependencies
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var fs = require("fs")
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var postcss = require("postcss")
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var customProperties = require("postcss-custom-properties")
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var calc = require("postcss-calc")
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// css to be processed
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var css = fs.readFileSync("input.css", "utf8")
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// process css
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var output = postcss()
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.use(customProperties())
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.use(calc())
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.process(css)
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.css
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```
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Using this `input.css`:
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```css
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:root {
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--main-font-size: 16px;
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}
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body {
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font-size: var(--main-font-size);
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}
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h1 {
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font-size: calc(var(--main-font-size) * 2);
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height: calc(100px - 2em);
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margin-bottom: calc(
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var(--main-font-size)
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* 1.5
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)
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}
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```
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you will get:
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```css
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body {
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font-size: 16px
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}
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h1 {
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font-size: 32px;
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height: calc(100px - 2em);
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margin-bottom: 24px
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}
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```
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Checkout [tests](test) for more examples.
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### Options
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#### `precision` (default: `5`)
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Allow you to definine the precision for decimal numbers.
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```js
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var out = postcss()
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.use(calc({precision: 10}))
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.process(css)
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.css
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```
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#### `preserve` (default: `false`)
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Allow you to preserve calc() usage in output so browsers will handle decimal precision themselves.
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```js
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var out = postcss()
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.use(calc({preserve: true}))
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.process(css)
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.css
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```
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#### `warnWhenCannotResolve` (default: `false`)
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Adds warnings when calc() are not reduced to a single value.
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```js
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var out = postcss()
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.use(calc({warnWhenCannotResolve: true}))
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.process(css)
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.css
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```
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#### `mediaQueries` (default: `false`)
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Allows calc() usage as part of media query declarations.
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```js
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var out = postcss()
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.use(calc({mediaQueries: true}))
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.process(css)
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.css
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```
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#### `selectors` (default: `false`)
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Allows calc() usage as part of selectors.
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```js
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var out = postcss()
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.use(calc({selectors: true}))
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.process(css)
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.css
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```
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Example:
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```css
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div[data-size="calc(3*3)"] {
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width: 100px;
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}
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```
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---
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## Contributing
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Work on a branch, install dev-dependencies, respect coding style & run tests before submitting a bug fix or a feature.
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```console
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$ git clone https://github.com/postcss/postcss-calc.git
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$ git checkout -b patch-1
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$ npm install
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$ npm test
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```
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## [Changelog](CHANGELOG.md)
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## [License](LICENSE)
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