How do I receive and use a JSON object on the client-side from the server (Node JS and Express)?

Question

I am trying to do something seemingly very simple but I'm having trouble working it out. Users can submit some text using a HTML form with POST method. This is then sent off to an API for processing, and returns with a JSON object. I then just want the app.js file to send this JSON object back so I can play around with it using JQuery. Here is the .post method in my app.js

app.post('/', function(req, res){
 console.log("starting app.post");

  // See User Modeling API docs. Path to profile analysis is /api/v2/profile
  // remove the last / from service_url if exist
  var parts = url.parse(service_url.replace(/\/$/,''));

  var profile_options = { host: parts.hostname,
    port: parts.port,
    path: parts.pathname + "/api/v2/profile",
    method: 'POST',
    headers: {
      'Content-Type'  :'application/json',
      'Authorization' :  auth }
    };

  // create a profile request with the text and the https options and call it
      create_profile_request(profile_options,req.body.content)(function(error,profile_string) {
        if (error) {res.render('home.html',{'error': error.message});
                        console.log("errormessage: "+error.message);
      }
    else {
      // parse the profile and format it
      var profile_json = JSON.parse(profile_string);
      var flat_traits = flatten.flat(profile_json.tree);      
      // Extend the profile options and change the request path to get the visualization
      var fileName="file 1"; //this will eventually be imported automatically
      //console.log(flat_traits);     
      var scoreObject={"title":fileName, "percentage":functions.matchPercentage(flat_traits)}
  res.send(scoreObject); //this is what I assume should send this back client-side      
          });
    }
  });
    });

// creates a request function using the https options and the text in content
// the function that return receives a callback
var create_profile_request = function(options,content) {
  return function (/*function*/ callback) {
    // create the post data to send to the User Modeling service
    var post_data = {
  'contentItems' : [{ 
    'userid' : 'dummy',
    'id' : 'dummyUuid',
    'sourceid' : 'freetext',
    'contenttype' : 'text/plain',
    'language' : 'en',
    'content': content
  }]
    };
// Create a request to POST to the User Modeling service
var profile_req = https.request(options, function(result) {
  result.setEncoding('utf-8');
  var response_string = '';

  result.on('data', function(chunk) {
    response_string += chunk;
  });

  result.on('end', function() {

    if (result.statusCode != 200) {
      var error = JSON.parse(response_string);
      console.log("status: "+result.statusCode);
      callback({'message': error.user_message}, null);
      console.log(error.user_message);
    } else
      callback(null,response_string);
  });
});

profile_req.on('error', function(e) {
  callback(e,null);
});

profile_req.write(JSON.stringify(post_data));
profile_req.end();
  }
 };

So I presume res.send is what passes the data across to the client-side, but then how do I receive the data on the client-side? This is my attempt at the JScript:

$.getJSON('/').done(function(data){
$('#resultsList').append('<li data-icon="arrow-r" data-iconpos="right" id="'+
        data.title+'">  <a href="#breakdownDialog"> <div id="cvResults"><h3>'+
        data.title+'</h3>   <span>'+data.percentage+
        '%</span></div></a><div id="output"></div></li>');
console.log(data.title+data.percentage);
}
});

I want to take some of the values from the JSON object and put them in a list on the existing HTML page. At the moment this just takes me to a different blank page that says Undefined. How should I grab the JSON data from the server?

EDIT: Here's the HTML form I am submitting the data with:

<form method="POST" id="submitForm">
                <fieldset>
                    <textarea id="textArea" required="true" rows="5" name="content"></textarea>
                    <button class="btn btn-block" type="submit">
                            Analyse         
                    </button>
                </fieldset>
                </form>

Answer 1

Are you sure that you are sending json with res.send()? Try to set header res.set('Content-Type', 'application/json') or use this res.json() instead of res.send()