var CSSParser = require("jscssp").CSSParser;
var cssParser = new CSSParser;
cssParser.parse("h1 {color: red}")
-> {cssRules: 
  [{type: 1
    , parsedCssText: 'h1 {\n  color: red;\n}'
    , declarations: {type: 1000
      , property: 'color'
      , values: [{value: 'red'
        , type: 1
        , name: null
        , parentRule: null
        , parentStyleSheet: [Circular]
        }
      ]
      , valueText: 'red'
      , priority: false
      , parsedCssText: 'color: red;'
      , parentStyleSheet: null
      , parentRule: null
      }
    , mSelectorText: 'h1'
    , parentStyleSheet: [Circular]
    , parentRule: null
    , currentLine: 0
    }
  ]
, variables: {}
}

$ npm install jscssp

git submodule update --init
open test/index.html

To see test results in the console run

node test/*_test.js

• CSSOM.js
• Sheet.js
• CodeMirror's CSS parser