var http = require("http"),
    fs = require('fs'),
    async = require('./js/async.js');

var onRequest = function(request,response) {
  response.writeHead(200,{ "Content-Type": "text/html; charset=utf-8" });

  var file;            // 'file' declared

  var main = function(callback) {
    fs.readFile('.\html\admin.html','utf-8',function(err,data) {
      file = data;     // 'file' is given content of admin.html
      console.log('2 >> ' + typeof file);
    });
    callback(null);
  }

  console.log('1 >> ' + typeof file);

  async.series([
    main
  ], function() {      // At this point 'file' is still undefined, that's odd
    response.end();    // 'cause it's a callback and should be fired after 'main'
    console.log('3 >> ' + typeof file);
  });
}

http.createServer(onRequest).listen(80);

1 >> undefined
3 >> undefined
2 >> string

1 >> undefined
2 >> string
3 >> string