title: node.js express: How can I know if a request is an AJAX request?
body: <p>Let's say I have a small piece of code:</p>
  
  <pre><code>var express = require('express');
  var app = express();
  
  app.get('/', function(req, res){
    //I want to acccess 'req' and get info whether it's an AJAX call
  });
  
  app.listen(3000);
  </code></pre>
  
  <p>When I go inside the app.get(..) function, I want to know if the get request sent is an AJAX call. What is the field in the object 'req' that can tell me this? </p>