如何读取错误描述？

我开发基于浏览器的多人游戏已经有一段时间了，我一直在测试不同环境(客户端办公室，公共 wifi 等)的不同端口的可访问性。一切都进行得很顺利，除了一件事: 我不知道如何读取错误没有。接收到错误事件时的描述。

客户端 websocket 是用 javascript 完成的。

例如:

// Init of websocket
websocket = new WebSocket(wsUri);
websocket.onerror = OnSocketError;
...etc...


// Handler for onerror:
function OnSocketError(ev)
{
output("Socket error: " + ev.data);
}

“ output”只是一个写入 div 的实用函数。

我得到的是 ev.data 的“未定义”。一向如此。我一直在谷歌周围，但似乎没有规格说明这个事件有什么参数，以及如何正确地阅读它。

感谢你们的帮助！

129470 次浏览
小开
最佳答案

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.

小开

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() + "<br />" + "The connection was opened");
};
websocket.onclose = function (event) {
var reason;
alert(event.code);
// See https://www.rfc-editor.org/rfc/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 [https://www.rfc-editor.org/rfc/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. <br /> 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() + "<br />" + "The connection was closed for reason: " + reason);
};
websocket.onmessage = function (event) {
$("#thingsThatHappened").html($("#thingsThatHappened").html() + "<br />" + "New message arrived: " + event.data);
};
websocket.onerror = function (event) {
$("#thingsThatHappened").html($("#thingsThatHappened").html() + "<br />" + "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/

小开

Potential stupid fix for those who throw caution to the wind: return a status code. The status code can be viewed from the onerror event handler by accessing the message property of the argument received by the handler. I recommend going with the 440s--seems to be free real estate.

"Unexpected server response: 440"

Little bit of regex does the trick:

const socket = new WebSocket(/* yuh */);


socket.onerror = e => {
const errorCode = e.message.match(/\d{3}/)[0];
// errorCode = '440'
// make your own rudimentary standard for error codes and handle them accordingly
};

Might be useful in a pinch, but don't come crying to me for any unforeseen repercussions.


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