title: i have already tried,but i don't no how to call the function in another file
body: <p>sir/madam exlain the flow of node.js from client to server with the dynamic parameters passing from userinterface to api's based up on these parameters we will get the output from api.for example sabre api etc..</p>
  
  <pre><code>exports.flightDestinations = function(req, res) {
      var callback = function(error, data) {
          if (error) {
              // Your error handling here
              console.log(error);
          } else {
              // Your success handling here
              // console.log(JSON.parse(data));
              res.send(JSON.parse(data));
  
          }
      };
  
      sabre_dev_studio_flight.airports_top_destinations_lookup({
          topdestinations: '50'
      }, callback);
  };
  </code></pre>
  
  <p>we want this value 50 from user...and how to give this value?and how to call this function in node.js.</p>