PostCSS Calc

PostCSS Calc lets you reduce calc() references whenever it's possible. This can be particularly useful with the PostCSS Custom Properties plugin.

When multiple units are mixed together in the same expression, the calc() statement is left as is, to fallback to the W3C calc() implementation.

Installation

npm install postcss-calc

Usage

// dependencies
var fs = require("fs")
var postcss = require("postcss")
var calc = require("postcss-calc")

// css to be processed
var css = fs.readFileSync("input.css", "utf8")

// process css
var output = postcss()
  .use(calc())
  .process(css)
  .css

Example (with PostCSS Custom Properties enabled as well):

// dependencies
var fs = require("fs")
var postcss = require("postcss")
var customProperties = require("postcss-custom-properties")
var calc = require("postcss-calc")

// css to be processed
var css = fs.readFileSync("input.css", "utf8")

// process css
var output = postcss()
  .use(customProperties())
  .use(calc())
  .process(css)
  .css

Using this input.css:

:root {
  --main-font-size: 16px;
}

body {
  font-size: var(--main-font-size);
}

h1 {
  font-size: calc(var(--main-font-size) * 2);
  height: calc(100px - 2em);
  margin-bottom: calc(
      var(--main-font-size)
      * 1.5
    )
}

you will get:

body {
  font-size: 16px
}

h1 {
  font-size: 32px;
  height: calc(100px - 2em);
  margin-bottom: 24px
}

Checkout tests for more examples.

Options

precision (default: 5)

Allow you to define the precision for decimal numbers.

var out = postcss()
  .use(calc({precision: 10}))
  .process(css)
  .css

preserve (default: false)

Allow you to preserve calc() usage in output so browsers will handle decimal precision themselves.

var out = postcss()
  .use(calc({preserve: true}))
  .process(css)
  .css

warnWhenCannotResolve (default: false)

Adds warnings when calc() are not reduced to a single value.

var out = postcss()
  .use(calc({warnWhenCannotResolve: true}))
  .process(css)
  .css

mediaQueries (default: false)

Allows calc() usage as part of media query declarations.

var out = postcss()
  .use(calc({mediaQueries: true}))
  .process(css)
  .css

selectors (default: false)

Allows calc() usage as part of selectors.

var out = postcss()
  .use(calc({selectors: true}))
  .process(css)
  .css

Example:

div[data-size="calc(3*3)"] {
  width: 100px;
}

Contributing

Work on a branch, install dev-dependencies, respect coding style & run tests before submitting a bug fix or a feature.

git clone [email protected]:postcss/postcss-calc.git
git checkout -b patch-1
npm install
npm test

Changelog

License