Error when using JSON.parse in node.js

I'm writing a simple program that makes a request to reddit, and gets back the page in JSON format. I do this by appending '.json' to the end of the reddit url. For example, if i wanted to get the page for my profile i would do "www.reddit.com/user/stebon24.json".

Here is my program so far. I will log and describe the error below.

var http = require('http');
var options = {
    host: 'www.reddit.com',
    path: ''
};

module.exports = function(username) {

    console.log(username);

    options.path = '/user/' + username + '.json';

    var userData;

    http.get(options, function(res) { 

        res.on('data', function(data) {
            userData += data;
            console.log(userData);
        });

        res.on('end', function() {
            userData = JSON.parse(userData);
            console.log(userData);
        });
    });
};

As for the error, it happens when the program gets to the point where it needs to run JSON.parse(). I know this because i can see it output the raw JSON from when i log the result on the 'data' event. Then this error is output...

undefined:1
undefined{"kind": "Listing", "data": {"modhash": "", "children": [{"kind": "t1
^
SyntaxError: Unexpected token u
    at Object.parse (native)
    at IncomingMessage.module.exports (/home/stephen/Desktop/karmacrawler/engine/crawlUser.js:23:20)
    at IncomingMessage.EventEmitter.emit (events.js:126:20)
    at IncomingMessage._emitEnd (http.js:366:10)
    at HTTPParser.parserOnMessageComplete [as onMessageComplete] (http.js:149:23)
    at Socket.socketOnData [as ondata] (http.js:1367:20)
    at TCP.onread (net.js:403:27)