thunk.js

var thunk = require('thunkify');
var delay = thunk(function(cb) {
  setTimeout(function() {
    console.log('delay end');
    cb();
  }, 1000);
});

var n = delay()

setTimeout(function() {
  console.log('set callback');
  n(function() {
    console.log('call!');
  });
}, 2000);