I have this working python websocket server:

#!/usr/bin/env python
from socket import *
HOST = ''
PORT = 8080
BUFSIZ = 1024
ADDR = (HOST, PORT)
tcpSerSock = socket(AF_INET, SOCK_STREAM)
tcpSerSock.bind(ADDR)
tcpSerSock.listen(5)
def loop():
 while True:
 print 'Waiting for connection...'
 tcpCliSock, addr = tcpSerSock.accept()
 print '...connected from :', addr
 while True:
 data = tcpCliSock.recv(BUFSIZ)
 if not data:
 break
 else:
 print 'data: ',data
 tcpSerSock.close()
try:
 loop()
except KeyboardInterrupt:
 tcpSerSock.close()

when I connect from the python client it works even if when I close the client the server crashes:

Waiting for connection...
Traceback (most recent call last):
 File "ledServer.py", line 27, in <module>
 loop()
 File "ledServer.py", line 16, in loop
 tcpCliSock, addr = tcpSerSock.accept()
 File "/usr/lib/python2.7/socket.py", line 202, in accept
 sock, addr = self._sock.accept()
 File "/usr/lib/python2.7/socket.py", line 170, in _dummy
 raise error(EBADF, 'Bad file descriptor')
socket.error: [Errno 9] Bad file descriptor

anyway when I run this javascript client:

window.onload = function(){
 ws = new WebSocket('ws://192.168.25.7:8080'); 
 ws.onmessage = function(event){document.write("message received"); alert(event.data); ws.close();} 
 ws.onopen = function(){document.write("open");} 
 ws.onclose = function(){document.write("close");}
 ws.onerror = function(){document.write("error");}
}

I get this on the server:

...connected from : ('192.168.25.25', 53747)
data: GET / HTTP/1.1
Host: 192.168.25.7:8080
Connection: Upgrade
Pragma: no-cache
Cache-Control: no-cache
Upgrade: websocket
Origin: file://
Sec-WebSocket-Version: 13
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36
Accept-Encoding: gzip, deflate
Accept-Language: it-IT,it;q=0.9,en-US;q=0.8,en;q=0.7,tr;q=0.6,nl;q=0.5
Sec-WebSocket-Key: pH4kNOzz1MYyi+oXmaFCcA==
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits

but even if the server says it is connected, on the client the onopen function is not executed, Chrome says that websocket status is "pending", and if I try to send a message to the server, I get:

Uncaught DOMException: Failed to execute 'send' on 'WebSocket': Still in CONNECTING state.

What am I doing wrong?