JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/bluebird/2.9.33/bluebird.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.0/lodash.min.js"></script>

JavaScript

var o = {};
o.dummy = function(path, encoding, cb){
  return cb(null, "file content here " + path + " " +encoding);
}

Promise.promisifyAll(o);

o.dummyAsync("a","b").then(function(data){
   console.log("HI", data); 
});

var part = _.bind(o.dummyAsync, o, "a1", "b2");
part().then(function(data){
   console.log("Hi2", data); 
});