Uncss Versions Save

• Fixed #407
• Fixed implementation details in the postcss plugin

• Fixed a bug in the handling of jsdom options.

• Added option to specify jsdom page-creation options.
• Output from the jsdom windows is now redirected to stderr by default.
• Added the output option to write to file, insted of stdout.
• Updated to PostCSS 7

Support for injecting JS on page load before uncss runs, as well as some bug fixes.

Fix regression causing selectors with multiple pseudo-classes to be ignored.

A bunch of internal cleanups, and removed support for older versions of Node.

Migrate from PhantomJS to JSDom, and update our package.json dependencies (cleaning up some warnings).

Fix a missing async dependency.

Sourcemap support, better parallelization, some CSS handling fixes:

• PostCSS rewrite to handle larger variety of CSS with source preservation (including sourcemap support!)
• Handle large number of HTML files better (though serialization)
• Better CSS handling (will trim vendor-specific prefixes if unused, can handle multiple animation names, etc)