Use autoprefixer synchronously

i want to use autoprefixer in my node application to compile css. for my specific needs, i want to call autoprefixer without callback or promise.

just plain :

var result = autoprefixer.process(css);

or

var result = myPrefixerWrap(css);

i am fighting with this for a while, can you help me please.

thank you

ps: i already tried postcss-js, but it result an json object for react use, and not pure css. for example {borderRadius:"5px"}

var prefixer    = postcssJs.sync([ autoprefixer ]);
var cssCompiled = postcss.parse(css);
var cssObject   = postcssJS.objectify(cssCompiled);
var autoResult  = prefixer(cssObject);