How to execute jsonp response? Or how to make a string to a function call?

Following scenario:

• I use Node.js to connect to an API.
• I fire a request and get a jsonp response back.

This response look like:

processResponse({"LoginResponse":{"@token":"x"}})

That's it. Just that line: A string/object/text.

I have also a function processResponse()

processResponse(data){
   console.log(data);
};

My Question: How to get that response executed, since it is just an object. I wish to 'parse' a string to a function call.

  client.methods.loginRequest(loginArgs, function(data,response){
      //response body as js object
      console.log(data);
      // processResponse({"LoginResponse":{"@token":"x"}})

      // now I wish to execute it.
      data;        // this doesn't work
      data.exec(); // this doesn't work
      ?            // what else
  });

  function processResponse(data){
      console.log(data);
  };

I hope there is a way?