project  - app - some files
        - build - index.js, index.html, etc.(I start the server by "node index.js")
        - node_modules - some modules
        - signup - some files to be minified
        - signin - some files to be minified
        - apache-cassandra-3.0.6 - bin, conf, etc.(downloaded from tarball)
        - package.json
        - webpack.config.js

var client = new cassandra.Client({contactPoints:['127.0.0.1:9042']});
                   OR
var client = new cassandra.Client({contactPoints:['127.0.0.1']});

var router = express.Router();
var insertUser = 'INSERT INTO keyspace.users (username, create_time, email, password) VALUES (?, ?, ?, ?);';

router.get"/", function(req, res) {
  res.sendFile(__dirname + '/index.html'); // This is working.
});

router.post("/signup", function(req, res) {
  var email = req.body.email;
  var password = req.body.password;
  client.execute(insertUser, [username, now(), email, password],
  { prepare: true }, function(err) {
    if (err) {
      console.log("error"); // I receive error.
    } else {
      console.log("success");
    }
  };