cssnano

What is cssnano?

cssnano is a modular minifier for CSS, which uses PostCSS for its plugin architecture. It is aimed at reducing the size of CSS files by applying various optimizations, such as removing whitespace, comments, and unnecessary prefixes, as well as merging rules and minifying values.

What are cssnano's main functionalities?

Preset Configuration

This code demonstrates how to use cssnano with its default preset to minify a CSS string. The 'process' method is called on the PostCSS instance with cssnano as a plugin.

const cssnano = require('cssnano');
const postcss = require('postcss');

postcss([cssnano()])
.process(css, { from: undefined })
.then(result => {
  console.log(result.css);
});

Custom Plugin Usage

This code shows how to use cssnano with other PostCSS plugins like autoprefixer. It demonstrates the use of a custom preset configuration for cssnano.

const cssnano = require('cssnano');
const autoprefixer = require('autoprefixer');
const postcss = require('postcss');

postcss([autoprefixer, cssnano({ preset: 'default' })])
.process(css, { from: undefined })
.then(result => {
  console.log(result.css);
});

Optimizing for Production

This code snippet illustrates how to use cssnano for production by disabling source maps and using the default preset for optimization.

const cssnano = require('cssnano');
const postcss = require('postcss');

postcss([cssnano({ preset: 'default' })])
.process(css, { from: undefined, map: false })
.then(result => {
  console.log(result.css);
});

Other packages similar to cssnano

clean-css

clean-css is a fast and efficient CSS optimizer for Node.js and the browser. It performs similar tasks to cssnano, such as minifying CSS, but it does not use PostCSS as its foundation. It provides its own API and set of features for optimizing CSS files.

purgecss

purgecss is a tool to remove unused CSS, which can be used in conjunction with CSS minifiers like cssnano. While cssnano focuses on optimizing the CSS that is already being used, purgecss helps to reduce file size by stripping out styles that are not used in your HTML or JavaScript files.

uglifycss

uglifycss is a simple, straightforward CSS minifier. It lacks the modularity and plugin system of cssnano but is easy to use for basic CSS minification tasks. It is suitable for projects that require a simpler setup without the need for extensive configuration or additional plugins.

README

A modular minifier, built on top of the PostCSS ecosystem.


cssnano is a modular minifier that aims to utilise small modules from the PostCSS ecosystem, rather than being an all-encompassing module that may be difficult to contribute to. Because it is written on top of PostCSS, it is able to do more than simple whitespace transforms - including advanced optimisations such as custom identifier reduction, z-index rebasing, and adjacent selector merging.

For further details check out the website:

• Installation guide for your build process.
• Full list of optimisations.
• Customise the output (options documentation).

Contributing

Pull requests are welcome. If you add functionality, then please add unit tests to cover it.

License

MIT © Ben Briggs