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CloseEvent: code property

files/en-us/web/api/closeevent/code/index.md

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{{APIRef("Websockets API")}}{{AvailableInWorkers}}

The code read-only property of the {{domxref("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.

<table class="no-markdown"> <thead> <tr> <th>Status code</th> <th>Meaning</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td><code>0</code>–<code>999</code></td> <td></td> <td>Not used.</td> </tr> <tr> <td><code>1000</code></td> <td>Normal Closure</td> <td> The connection successfully completed the purpose for which it was created. </td> </tr> <tr> <td><code>1001</code></td> <td>Going Away</td> <td> 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. </td> </tr> <tr> <td><code>1002</code></td> <td>Protocol error</td> <td> The endpoint is terminating the connection due to a protocol error. </td> </tr> <tr> <td><code>1003</code></td> <td>Unsupported Data</td> <td> 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.) </td> </tr> <tr> <td><code>1004</code></td> <td>Reserved</td> <td> <strong>Reserved.</strong> A meaning might be defined in the future. </td> </tr> <tr> <td><code>1005</code></td> <td>No Status Received</td> <td> <strong>Reserved.</strong> Indicates that no status code was provided even though one was expected. </td> </tr> <tr> <td><code>1006</code></td> <td>Abnormal Closure</td> <td> <strong>Reserved.</strong> Indicates that a connection was closed abnormally (that is, with no close frame being sent) when a status code is expected. </td> </tr> <tr> <td><code>1007</code></td> <td>Invalid frame payload data</td> <td> 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). </td> </tr> <tr> <td><code>1008</code></td> <td>Policy Violation</td> <td> 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. </td> </tr> <tr> <td><code>1009</code></td> <td>Message Too Big</td> <td> The endpoint is terminating the connection because a data frame was received that is too large. </td> </tr> <tr> <td><code>1010</code></td> <td>Mandatory Ext.</td> <td> The client is terminating the connection because it expected the server to negotiate one or more extension, but the server didn't. </td> </tr> <tr> <td><code>1011</code></td> <td>Internal Error</td> <td> The server is terminating the connection because it encountered an unexpected condition that prevented it from fulfilling the request. </td> </tr> <tr> <td><code>1012</code></td> <td><a href="https://mailarchive.ietf.org/arch/msg/hybi/P_1vbD9uyHl63nbIIbFxKMfSwcM/">Service Restart</a></td> <td> The server is terminating the connection because it is restarting. </td> </tr> <tr> <td><code>1013</code></td> <td><a href="https://mailarchive.ietf.org/arch/msg/hybi/P_1vbD9uyHl63nbIIbFxKMfSwcM/">Try Again Later</a></td> <td> The server is terminating the connection due to a temporary condition, e.g., it is overloaded and is casting off some of its clients. </td> </tr> <tr> <td><code>1014</code></td> <td><a href="https://mailarchive.ietf.org/arch/msg/hybi/VOLI2xp4tzFnIFYespe6oOtpFXA/">Bad Gateway</a></td> <td> 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. </td> </tr> <tr> <td><code>1015</code></td> <td>TLS handshake</td> <td> <strong>Reserved.</strong> Indicates that the connection was closed due to a failure to perform a TLS handshake (e.g., the server certificate can't be verified). </td> </tr> <tr> <td><code>1016</code>–<code>2999</code></td> <td></td> <td> For definition by future revisions of the WebSocket Protocol specification, and for definition by extension specifications. </td> </tr> <tr> <td><code>3000</code>–<code>3999</code></td> <td></td> <td> For use by libraries, frameworks, and applications. These status codes are <a href="https://www.iana.org/assignments/websocket/websocket.xml#close-code-number">registered directly with IANA</a>. The interpretation of these codes is undefined by the WebSocket protocol. </td> </tr> <tr> <td><code>4000</code>–<code>4999</code></td> <td></td> <td> 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. </td> </tr> </tbody> </table>

Examples

The following example prints the value of code to the console.

js
WebSocket.onclose = (event) => {
  console.log(event.code);
};

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also