CSS parser for JavaScript?

I'd like to parse a blob of CSS into an AST so I can add prefixes to certain CSS directives.

Is there a CSS parser for JavaScript or Node that will do this?

I've searched NPM. The only useful result I've found is parser-lib, but it's stream-based and it looks like I'll need to write my own emitter for every CSS node.

Update: I also found JSCSSP, but it has no documentation...

Also worth mentioning is LESS. While it is primarily a (fantastic) extension to CSS, the LESS parser does give you access to the AST.

A pure CSS stylesheet is also a valid LESS stylesheet, so you can start with what you have now and ease in to LESS' extensions.

Update: I previously mentioned JSCSSP, which is buggy seems to be abandoned. Obviously enough, the css module on NPM is the best:

css = require 'css'

input = '''
  body {
    font-family: sans-serif;
  }
  #thing.foo p.bar {
    font-weight: bold;
  }
'''

obj = css.parse input
sheet = obj.stylesheet

for rule in sheet.rules
  rule.selectors = ('#XXX ' + s for s in rule.selectors)

console.log css.stringify(obj)

Output:

#XXX body {
  font-family: sans-serif;
}
#XXX #thing.foo p.bar {
  font-weight: bold;
}

For what it's worth, JSDOM uses CSSOM.

http://www.glazman.org/JSCSSP/

http://jsfiddle.net/cYEgT/

sheet is sort of like an AST.

Here is our open source CSS parser css.js

Here is a simple parsing example : 

<script type="text/javascript">
    var cssString = ' .someSelector { margin:40px 10px; padding:5px}';
    //initialize parser object
    var parser = new cssjs();
    //parse css string
    var parsed = parser.parseCSS(cssString);

    console.log(parsed);
</script>

To stringify parsed data structure into CSS string after editing 

var newCSSString = parser.getCSSForEditor(parsed);

Main features of our CSS parser is :

  • It is lightweight.
  • It outputs easy to understand javascript object. No complex AST.
  • It is battle tested(and unit tested also) and constantly used in our products(JotForm Form Designer).
  • It supports media queries, keyframes and font-face rules.
  • It preserves comments while parsing.