php Ratchet websocket javascript连接失败

我有telnet工作，但当我尝试聊天教程的下一部分时，javascript无法连接

UPDATE ERROR MESSAGE FROM GOOGLE CHROME

WebSocket connection to 'ws://localhost:8080/' failed: Error during WebSocket handshake: Unexpected response code: 200

PHP代码

 /* chat-server.php */
 use Ratchet\Server\IoServer;
 use Ratchet\Http\HttpServer;
 use Ratchet\WebSocket\WsServer;
 use MyApp\Chat;

require dirname(__DIR__) . '/vendor/autoload.php';

$server = IoServer::factory(
    new HttpServer(
        new WsServer(
            new Chat()
        )
    ),
    8080
);

$server->run();





/* Chat.php */

namespace MyApp;

use Ratchet\MessageComponentInterface;
use Ratchet\ConnectionInterface;

class Chat implements MessageComponentInterface {

protected $clients;

public function __construct() {
    $this->clients = new \SplObjectStorage;
}

public function onOpen(ConnectionInterface $conn) {
    // Store the new connection to send messages to later
    $this->clients->attach($conn);

    echo "New connection! ({$conn->resourceId})\n";
}

public function onMessage(ConnectionInterface $from, $msg) {
    $numRecv = count($this->clients) - 1;
    echo sprintf('Connection %d sending message "%s" to %d other connection%s' . "\n"
            , $from->resourceId, $msg, $numRecv, $numRecv == 1 ? '' : 's');

    foreach ($this->clients as $client) {
        if ($from !== $client) {
            // The sender is not the receiver, send to each client connected
            $client->send($msg);
        }
    }
}

public function onClose(ConnectionInterface $conn) {
    // The connection is closed, remove it, as we can no longer send it messages
    $this->clients->detach($conn);

    echo "Connection {$conn->resourceId} has disconnected\n";
}

public function onError(ConnectionInterface $conn, \Exception $e) {
    echo "An error has occurred: {$e->getMessage()}\n";

    $conn->close();
}

}  

在运行命令行php bin/chat-server.php之后，接下来我将在javascript控制台中运行该命令行

var conn = new WebSocket('ws://localhost:8080');
conn.onopen = function(e) {
    console.log("Connection established!");
};

conn.onmessage = function(e) {
    console.log(e.data);
};

但我收到javascript错误，无法连接

UPDATE ERROR MESSAGE FROM GOOGLE CHROME

WebSocket connection to 'ws://localhost:8080/' failed: Error during WebSocket handshake: Unexpected response code: 200