postcss-calc
Advanced tools
Package description
The postcss-calc npm package is a PostCSS plugin that reduces CSS calc() function to the maximum, whenever it's possible. It simplifies calculations in CSS files and optimizes them during the build process, making the final CSS file lighter and easier for browsers to parse.
Simplification of calc expressions
This feature allows the simplification of calc expressions in CSS, reducing them to their simplest form. For example, if you have a calculation based on CSS custom properties or simple arithmetic, postcss-calc can compute these values at build time, resulting in cleaner and more efficient CSS.
css
.post {
--gap: 20px;
padding: calc(var(--gap) * 2);
}
/* becomes */
.post {
padding: 40px;
}Optimization of complex calculations
For more complex calculations that cannot be fully simplified without context (like viewport sizes or percentages), postcss-calc optimizes the expression to ensure it's as efficient as possible without altering the intended result.
css
.banner {
width: calc(100% - 80px);
}
/* becomes */
.banner {
width: calc(100% - 80px);
}cssnano is a modular CSS minifier that includes functionalities similar to postcss-calc as part of its optimizations. It uses PostCSS to analyze and rewrite CSS files, reducing their size. While cssnano includes a broader range of optimizations, postcss-calc focuses specifically on the optimization of calc() functions.
postcss-custom-properties is another PostCSS plugin that allows you to use CSS custom properties (variables) in your stylesheets. It can transform these properties into static values, similar to how postcss-calc simplifies calc() expressions. However, it focuses on variables rather than calculations.
Readme
PostCSS plugin to reduce
calc().
Particularly useful with the postcss-custom-properties
npm install postcss-calc
var postcss = require("postcss")
var calc = require("postcss-calc")
var css = postcss()
.use(calc())
.process(cssString)
.css
This reduce calc() references whenever it's possible.
This can be particularly useful with the postcss-custom-properties plugin.
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.
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("style.css", "utf8")
var output = postcss()
.use(customProperties())
.use(calc())
.process(css)
.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);
}
yields:
body {
font-size: 16px
}
h1 {
font-size: 32px;
height: calc(100px - 2em)
}
See unit tests for a better example.
Work on a branch, install dev-dependencies, respect coding style & run tests before submitting a bug fix or a feature.
git clone https://github.com/postcss/postcss-calc.git
git checkout -b patch-1
npm install
npm test
FAQs
PostCSS plugin to reduce calc()
We found that postcss-calc demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 7 open source maintainers collaborating on the project.
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