Web/API/CloseEvent

A CloseEvent is sent to clients using WebSockets when the connection is closed. This is delivered to the listener indicated by the WebSocket object's onclose attribute.

Constructor

CloseEvent(): Creates a new CloseEvent.

Properties

This interface also inherits properties from its parent, Event.

CloseEvent.code Read only

Returns an unsigned short containing the close code sent by the server. The following values are permitted status codes. The following definitions are sourced from the IANA website [Ref]. Note that the 1xxx codes are only WebSocket-internal and not for the same meaning by the transported data (like when the application-layer protocol is invalid). The only permitted codes to be specified in Firefox are 1000 and 3000 to 4999 [Source, Bug].

Status code	Name	Description
`0`–`999`		Reserved and not used.
`1000`	Normal Closure	Normal closure; the connection successfully completed whatever 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. 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. Used to indicate 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`	Missing Extension	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. [Ref]
`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. [Ref]
`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`–`1999`		Reserved for future use by the WebSocket standard.
`2000`–`2999`		Reserved for use by WebSocket extensions.
`3000`–`3999`		Available for use by libraries and frameworks. May not be used by applications. Available for registration at the IANA via first-come, first-serve.
`4000`–`4999`		Available for use by applications.

CloseEvent.reason Read only

Returns a DOMString indicating the reason the server closed the connection. This is specific to the particular server and sub-protocol.

CloseEvent.wasClean Read only

Returns a Boolean that Indicates whether or not the connection was cleanly closed.

Methods

This interface also inherits methods from its parent, Event.

CloseEvent.initCloseEvent() ' ': Initializes the value of a CloseEvent created. If the event has already being dispatched, this method does nothing. Do not use this method anymore, use the CloseEvent() constructor instead.

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'CloseEvent' in that specification.	Living Standard	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`CloseEvent`	Chrome Full support 13	Edge Full support 12	Firefox Full support 8 Notes' Full support 8 Notes' Notes' Prior to Firefox 12, the close code `CLOSE_NORMAL` was used when the channel was closed due to an unexpected error or unspecified error condition. Notes' Prior to Firefox 8, the `WebSocket` close event was sent to the listener as a simple event.	IE Full support 10	Opera Full support 12.1	Safari Full support 6	WebView Android Full support ≤37	Chrome Android Full support 18	Firefox Android Full support 8	Opera Android Full support 12.1	Safari iOS Full support 6	Samsung Internet Android Full support 1.0
`CloseEvent()` constructor	Chrome ?	Edge ?	Firefox Full support 8	IE ?	Opera ?	Safari ?	WebView Android ?	Chrome Android ?	Firefox Android Full support 8	Opera Android ?	Safari iOS ?	Samsung Internet Android ?
`initCloseEvent` Experimental'Non-standard'	Chrome No support No	Edge No support 12 — 79	Firefox No support 8 — 41	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android No support 8 — 41	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No

Legend

Full support: Full support
No support: No support
Compatibility unknown: Compatibility unknown
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
Non-standard. Expect poor cross-browser support.': Non-standard. Expect poor cross-browser support.
See implementation notes.': See implementation notes.