title: Sending response after fs.readFile has finished executing iteratively
body: <p>I have the following code</p>
  
  <pre><code>var express = require('express');
  var Promise = require('bluebird');
  var fs = Promise.promisifyAll(require('fs'));
  var path = require("path");
  var langs = fs.readdirSync({directory having multiple directories});
  var arr = [];
  for(var v in langs){
      var filename = config.path.storage + "/" + langs[v] +"/assets/_assets.json";
          fs.readFile(filename, "utf8", function(err, data) {
          if (err) throw err;
          res.write(data);
          //res.end();
      });
  }
  res.end();
  </code></pre>
  
  <p>What I want to do is, once all the files in the directories (lang in this case - langs contains: <strong><em>[ 'ar-dz', 'en-gb', 'en-us' ]</em></strong>) are read, I want to do a res.send() to the client.</p>
  
  <p>I tried to promisify the 'fs' module via 'bluebird' module. I assume the callback in fs.readFileAsync() is causing the problem, is there a way around it?</p>