How to pass this json data from server to controller? Nodejs / AngularJS

I am successfully getting json data from a web API. It is logging correctly to server console, but when I pas it to client it is coming as blank [].

What am I doing wrong?

app.get('/balance', function(req, res) {

  var poloniexExchange = new Cryptox(
    "poloniex", {
      key: 'IGVRQCXB',
      secret: '93b5686d9ef'
    });

  //get all account balances
  poloniexExchange.getBalance({
    account: 'all'
  }, function(err, balance) {
    if (err)
      console.log(err);
    if (!err)

      console.log(balance.data[0].total); //logging all json data
    res.json(balance.data[0].total); 
  });
});

app.controller('websocketController', function($scope, $http) {

  $http.get("/balance")
    .then(function(response) {

        console.log(response.data); //logging '[]'

    });
});

I need to pass balance.data[0].total from server to controller. What am I doing wrong and How can I make this work?

via chuckieDub