4.1.0 • Public • Published


A CSS pre-processor, really simple to set up, sort of like cssnext used to be.

Back when we were young, cssnext used to be pretty simple: you installed it, you ran it, it worked. Nowadays, cssnext has evolved to build atop PostCSS, with lots of configuration coming with.

I have nothing against that move. It's a lot more powerful and flexible, and overall I think it is absolutely the right thing to do. But I have lots of projects, and they all need a default that's pretty much what cssnext used to be. So what cssn does is pretty much that: use cssnext and PostCSS with a default setup that matches what I need. It's a whole lot fewer direct dependencies to worry about, and a way to centralise options I like (such as being safe out of the box when minifying).

This is for you if you like these defaults and don't want to think too much about your CSS pre-processing; if you prefer the flexibility and power stick to the full PostCSS stack!


The usual:

npm install --save cssn


cssn [options] <input> <output>

When NODE_ENV is set to production, it minifies and does not report errors; otherwise it does not minify but reports errors. Due to this behaviour, it (currently) produces no source maps.

Options include:

  • -w, --watch: enter watch mode


You can use cssn as a library. It exports two functions:

  • async cssnow (input, output, { watcher, root }). This is the default export. Only input is required, it is a path to a file to process. output is the path to write to. watcher is a boolean that turns on watch mode, and root is a path resolve imports from (you should almost never need this). It resolves to the processed CSS as a string.
  • async processCSS (css, { input, output, root, production }). css is a string of CSS to process. Both input and output are only useful if you wish to do error reporting that includes source paths. root is the same as in the previous one. production is a boolean to set production mode independently of NODE_ENV.

Global installation

You may install it globally if you wish to (with npm install -g cssn), it will just work.


npm i cssn

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  • robin.berjon