无法确定websocket

Question

我在WebSockets和Django频道上有一个教程页面。 以下是前端代码：

var ws_scheme = window.location.protocol == "https:" ? "wss" : "ws";
var chat_socket = new ReconnectingWebSocket(ws_scheme + '://' + window.location.host + "/chat" + window.location.pathname);

URLs.py

urlpatterns = [
    url(r'^$',  views.about, name='about'),
    url(r'^new/$', views.new_room, name='new_room'),
    url(r'^(?P<label>[\w-]{,50})/$', views.chat_room, name='chat_room'),
]

views.py

def chat_room(request, label):
    # If the room with the given label doesn't exist, automatically create it
    # upon first visit (a la etherpad).
    room, created = Room.objects.get_or_create(label=label)

    # We want to show the last 50 messages, ordered most-recent-last
    messages = reversed(room.messages.order_by('-timestamp')[:50])

    return render(request, "chat/room.html", {
        'room': room,
        'messages': messages,
    })

为什么我们使用以下内容？

"/chat" + window.location.pathname);

据我所知，此URL是WebSocket服务器的位置。但是这个URL如何定位，因为我们没有在任何地方指定任何这样的模式？