ReferenceError: response is not defined

Server running at http://<workspace-url>/
/Users/briankaty1/Dropbox/JavaScript/simple_node_site/renderer.js:14
  response.write(fileContents);
  ^

ReferenceError: response is not defined
    at Object.view (/Users/briankaty1/Dropbox/JavaScript/simple_node_site/renderer.js:14:3)
    at Object.home (/Users/briankaty1/Dropbox/JavaScript/simple_node_site/router.js:11:12)
    at Server.<anonymous> (/Users/briankaty1/Dropbox/JavaScript/simple_node_site/app.js:36:10)
    at emitTwo (events.js:106:13)
    at Server.emit (events.js:191:7)
    at HTTPParser.parserOnIncoming [as onIncoming] (_http_server.js:546:12)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:99:23)

var fs = require("fs");
//Function that handles the reading of files and merge in value.

// read from file and get a string

//merge values in to a string.

function view(templateName, values, reponse) {
  //Read from the template file
  var fileContents = fs.readFileSync('./views/' + templateName + '.html');
  //Insert values in to the content

  //write out the contents to the response.
  response.write(fileContents);

}

module.exports.view = view;

var Profile = require("./profile.js");
var renderer = require("./renderer.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'});
  renderer.view("header", {}, response);
  response.write("Search\n");
  response.end('Footer\n');
//  - if url == "/" && POST
//  redirect to /:username
    }
}

function user(request, response) {
  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 need.
      var values = {
        avatarUrl: profileJSON.gravatar_url,
        username: profileJSON.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');
    });
    /**
    * If a parsing, network or HTTP error occurs an
    * error object is passed in to the handler or callback
    **/
    studentProfile.on("error", function(error){
      //show error
      response.write(error.message + "\n");
      response.end('Footer\n');
    });
  }
}

//## Handle HTTP route GET /:username i.e. /chalkers


module.exports.home = home;
module.exports.user = user;