Node.js - asynchronous module loading

Question

Is it possible to load a Node.js module asynchronously?

This is the standard code:

var foo = require(\"./foo.js\"); // waiting for I/O
foo.bar();
         


        

Answer 1

Andrey's code below is the simplest answer which works, but his had a small mistake so I'm posting the correction here as answer. Also, I'm just using callbacks, not bluebird / promises like Andrey's code.

/* 1. Create a module that does the async operation - request etc */

// foo.js + callback:
module.exports = function(cb) {
   setTimeout(function() {
      console.log('module loaded!');
      var foo = {};
      // add methods, for example from db lookup results
      foo.bar = function(test){
          console.log('foo.bar() executed with ' + test);
      };
      cb(null, foo);

   }, 1000);
}

/* 2. From another module you can require the first module and specify your callback function */

// usage
require("./foo.js")(function(err, foo) {
    foo.bar('It Works!');
});

/* 3. You can also pass in arguments from the invoking function that can be utilised by the module - e.g the "It Works!" argument */