modularize

1_original.js

var async = require('async');
var p = 
  [ function (cb) { redis.get('key1', cb); }
  , function (cb) { couchdb.get('key2', cb); }
  ];
async.parallel(p, function (err, results) {
  console.log(results[0]);
  console.log(results[1]);
});

2_getter.js

var async = require('async');
module.exports = function (key, cb) {
  var p = 
    [ function (cb) { redis.get(key, cb); }
    , function (cb) { couchdb.get(key, cb); }
    ];
  async.parallel(p, function (err, results) {
    cb(err, results);
  });
};

3_main.js

var getter = require('2_getter');
var cb = function (err, results) {
  console.log(results[0]);
  console.log(results[1]);
};
getter("key1", cb);
getter("key2", cb);