Got a bit lost on the way, profile not defined.

router.js

var Profile = require("./profile.js");


//Handle HTTP route GET / and POST / i.e. Home
function home(request, response) {
   //if url == "/" && GET
   if(request.url ==="/") {
     //show search
      response.writeHead(200, {'Content-Type': 'text/plain'});

      response.write("Header\n");
      response.write("Search\n")
      response.end("Footer\n");


   }
   //if url == "/" && POST
     //redirect to :/username   
}

function user(request, response) {

 // if url == "/...."
 var username = request.url.replace("/", "");

 if(username.length > 0) {
     response.writeHead(200, {'Content-Type': 'text/plain'});

      response.write("Header\n");
          //get JSON from Treehouse
          var studentProfile = new Profile(username);

            //on "end"
            studentProfile.on("end", function(profileJSON) {
                //show profile

               //store the values which we neeed
                var values = {
                    avatarUrl:  profileJSON.gravatar_url,
                    username: profile.JSON.profile_name,
                    badges: profileJSON.badges.length,
                    javascriptPoints: profileJSON.points.JavaScript
                }

                //simple response           
                response.write(values.username + " has " + values.badges + " badges\n");
                response.end("Footer\n");
    });

        //on "error"
    studentProfile.on("error", function(error) {
        //show error
      response.write(error.message + "\n"); 
      response.end("Footer\n");

    });


 }

}

//export routes to app.js
module.exports.home = home;
module.exports.user = user;