A Rework plugin that tests whether a chunk of CSS exceeds IE < 10's limit of 4095 selectors.
Install with npm:
npm install rework-ie-limits
As a Rework plugin:
var rework = require('rework');
var ieLimits = require('rework-ie-limits');
var css = rework(cssinput).use(ieLimits);
It will throw an Error
if the limit has been exceeded.
Note that the plugin is extremely conservative. It will assume that ALL selectors (and those within any media query) are supported and applied by each version of IE < 10. Therefore, there will be some false positives as you approach the limit.
For CI:
npm test
For development:
npm run watch