Websocket onerror - how to read error description

Question

I ve been developing browser-based multi player game for a while now and I ve been testing different ports accessibility in various environment  client s office  public wifi etc    All is going quite well  except one thing  I can t figure out is how to read error no  or description when onerror event is received   Client websocket is done in javascript   For example      Init of websocket websocket   new WebSocket wsUri   websocket onerror   OnSocketError     etc        Handler for onerror  function OnSocketError ev        output  Socket error      ev data        output  is just some utility function that writes into a div   What I am getting is  undefined  for ev data  Always  And I ve been googling around but it seems there s no specs on what params this event has and how to properly read it   Any help is appreciated

User · Accepted Answer

The error Event the onerror handler receives is a simple event not containing such information      If the user agent was required to fail the WebSocket connection or the WebSocket connection is closed with prejudice  fire a simple event named error at the WebSocket object    You may have better luck listening for the close event  which is a CloseEvent and indeed has a CloseEvent code property containing a numerical code according to RFC 6455 11 7 and a CloseEvent reason string property   Please note however  that CloseEvent code  and CloseEvent reason  are limited in such a way that network probing and other security issues are avoided

User · Answer

Alongside nmaier s answer  as he said you ll always receive code 1006  However  if you were to somehow theoretically receive other codes  here is code to display the results  via RFC6455    you will almost never get these codes in practice so this code is pretty much pointless  var websocket  if   WebSocket  in window        websocket   new WebSocket  ws   yourDomainNameHere org          websocket onopen   function  event                thingsThatHappened   html     thingsThatHappened   html       lt br   gt      The connection was opened               websocket onclose   function  event            var reason          alert event code              See http   tools ietf org html rfc6455 section-7 4 1         if  event code    1000              reason    Normal closure  meaning that the purpose for which the connection was established has been fulfilled            else if event code    1001              reason    An endpoint is   going away    such as a server going down or a browser having navigated away from a page            else if event code    1002              reason    An endpoint is terminating the connection due to a protocol error           else if event code    1003              reason    An endpoint is terminating the connection because it has received a type of data it cannot accept  e g   an endpoint that understands only text data MAY send this if it receives a binary message             else if event code    1004              reason    Reserved  The specific meaning might be defined in the future            else if event code    1005              reason    No status code was actually present            else if event code    1006             reason    The connection was closed abnormally  e g   without sending or receiving a Close control frame           else if event code    1007              reason    An endpoint is terminating the connection because it has received data within a message that was not consistent with the type of the message  e g   non-UTF-8  http   tools ietf org html rfc3629  data within a text message             else if event code    1008              reason    An endpoint is terminating the connection because it has received a message that   violates its policy    This reason is given either if there is no other sutible reason  or if there is a need to hide specific details about the policy            else if event code    1009             reason    An endpoint is terminating the connection because it has received a message that is too big for it to process            else if event code    1010     Note that this status code is not used by the server  because it can fail the WebSocket handshake instead              reason    An endpoint  client  is terminating the connection because it has expected the server to negotiate one or more extension  but the server didn t return them in the response message of the WebSocket handshake   lt br   gt  Specifically  the extensions that are needed are      event reason          else if event code    1011              reason    A server is terminating the connection because it encountered an unexpected condition that prevented it from fulfilling the request            else if event code    1015              reason    The connection was closed due to a failure to perform a TLS handshake  e g   the server certificate can t be verified             else             reason    Unknown reason                thingsThatHappened   html     thingsThatHappened   html       lt br   gt      The connection was closed for reason      reason              websocket onmessage   function  event                thingsThatHappened   html     thingsThatHappened   html       lt br   gt      New message arrived      event data              websocket onerror   function  event                thingsThatHappened   html     thingsThatHappened   html       lt br   gt      There was an error with your websocket              else       alert  Websocket is not supported by your browser        return     websocket send  Yo wazzup     websocket close      See http   jsfiddle net gr0bhrqr

[javascript] Websocket onerror - how to read error description?

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