CloseEvent: code property
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers.
The code read-only property of the CloseEvent interface returns a WebSocket connection close code indicating the reason the connection was closed.
Value
An integer WebSocket connection close code in the range 1000 - 4999, indicating the reason the connection was closed.
| Status code | Meaning | Description |
|---|---|---|
0–999 |
Not used. | |
1000 |
Normal Closure | The connection successfully completed the purpose for which it was created. |
1001 |
Going Away | The endpoint is going away, either because of a server failure or because the browser is navigating away from the page that opened the connection. |
1002 |
Protocol error | The endpoint is terminating the connection due to a protocol error. |
1003 |
Unsupported Data | The connection is being terminated because the endpoint received data of a type it cannot accept. (For example, a text-only endpoint received binary data.) |
1004 |
Reserved | Reserved. A meaning might be defined in the future. |
1005 |
No Status Received | Reserved. Indicates that no status code was provided even though one was expected. |
1006 |
Abnormal Closure | Reserved. Indicates that a connection was closed abnormally (that is, with no close frame being sent) when a status code is expected. |
1007 |
Invalid frame payload data | The endpoint is terminating the connection because a message was received that contained inconsistent data (e.g., non-UTF-8 data within a text message). |
1008 |
Policy Violation | The endpoint is terminating the connection because it received a message that violates its policy. This is a generic status code, used when codes 1003 and 1009 are not suitable. |
1009 |
Message Too Big | The endpoint is terminating the connection because a data frame was received that is too large. |
1010 |
Mandatory Ext. | The client is terminating the connection because it expected the server to negotiate one or more extension, but the server didn't. |
1011 |
Internal Error | The server is terminating the connection because it encountered an unexpected condition that prevented it from fulfilling the request. |
1012 |
Service Restart | The server is terminating the connection because it is restarting. |
1013 |
Try Again Later | The server is terminating the connection due to a temporary condition, e.g., it is overloaded and is casting off some of its clients. |
1014 |
Bad Gateway | The server was acting as a gateway or proxy and received an invalid response from the upstream server. This is similar to 502 HTTP Status Code. |
1015 |
TLS handshake | Reserved. Indicates that the connection was closed due to a failure to perform a TLS handshake (e.g., the server certificate can't be verified). |
1016–2999 |
For definition by future revisions of the WebSocket Protocol specification, and for definition by extension specifications. | |
3000–3999 |
For use by libraries, frameworks, and applications. These status codes are registered directly with IANA. The interpretation of these codes is undefined by the WebSocket protocol. | |
4000–4999 |
For private use, and thus can't be registered. Such codes can be used by prior agreements between WebSocket applications. The interpretation of these codes is undefined by the WebSocket protocol. |
Examples
The following example prints the value of code to the console.
js
WebSocket.onclose = (event) => {
console.log(event.code);
};
Specifications
| Specification |
|---|
| WebSockets # ref-for-dom-closeevent-code② |
Browser compatibility
| desktop | mobile | server | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
code
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
See also
- RFC 6455 (the WebSocket Protocol specification)
- WebSocket Close Code Number Registry (IANA)