const next = require('postcss-cssnext'); const modules = require('postcss-modules'); const postcss = require('postcss'); const processCss = function(file, done) { postcss([ next, modules({ getJSON: function(filename, json) { file.rename(file.path + '.json') done(JSON.stringify(json)) } }) ]).process(file.content, { from: file.path, to: file.path }).catch(function(err) { throw err }) }