How to use an excellent module "deasync" which makes async function to sync function easily.

deasync-example.js

/**
 NOTE: deasync can not use on browser.
*/
var deasync = require('deasync');

// any async function error-first callback styled
function asyncFn(p, cb) {
  let res = "hello " + p;
  let err = null;
  return cb && cb(err, res);
}

/** Use as async */
asyncFn("async world", (err, res) => {
  console.log("asyncFn callback:", res);
});

/** Use as sync! */
let syncFn = deasync(asyncFn);
let result = syncFn("sync world");
console.log("syncFn result:", result);


/*
 Result:
 asyncFn callback: hello async world
 syncFn result: hello sync world
*/