title: nodejs express read file and return response asynchronously
body: <p>I want to do something like this</p>
  
  <pre><code> router.get('/getforecast/:stationShortCode', function(req,res){
   var stationShortCode = req.params.stationShortCode;
  
   var fs = require('fs');
   fs.readFile("data/wx.hourly.txt", "utf8", function(err, data){
      if(err) throw err;
       //do operation on data that generates say resultArray;
       return resultArray;
    });
  
   res.send(resultArray);
  
  });
  </code></pre>
  
  <p>obviously, <code>res.send</code> is called synchronously, whereas the file reads async. Is there a clever solution to this? Am I forced to actually pass in <code>res</code>?</p>