javascript - Is it possible to handle both async and sync function results inside a sync function in node.js? -

i'm working on library pre-processes less, stylus, etc. preprocessors can both async , sync in nature. because result used in build stage, writing blocking code here not issue.

because preprocessors sync, , library expects sync functions down chain, wondering if it's somehow possible wrap preprocessor functions inside sync function can handle both sync , async results preprocessing function?

basically possible this, somehow?

syncfn = function(contents) {   var res = syncorasyncfn(contents, function(err, contents) {     res = contents   })   // .. magic here waits results of syncorasyncfn   return res; // return result function async or sync } 

sorry, that's impossible. whenever block of code running nothing can run inbetween, i.e. there no real parallelism in nodejs. therefore whatever do: res = contents line can fire after syncfn finishes whatever does, i.e. after synchronous operations finish job in block of code.

this forces nodejs programmers use callback pattern, example:

syncfn = function(contents, callback) {   syncorasyncfn(contents, function(err, contents) {     callback(contents);   }) }