WebSocket: close event

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.

The close event is fired when a connection with a WebSocket is closed.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

js
addEventListener("close", (event) => {});

onclose = (event) => {};

Event type

Event properties

In addition to the properties listed below, properties from the parent interface, Event, are available.

code Read only

Returns an unsigned short containing the close code sent by the server.

reason Read only

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

wasClean Read only

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

Examples

You might want to know when the connection has been closed so that you can update the UI or, perhaps, save data about the closed connection. Given that you have a variable called exampleSocket that refers to an opened WebSocket, this handler would handle the situation where the socket has been closed.

js
exampleSocket.addEventListener("close", (event) => {
  console.log("The connection has been closed successfully.");
});

You can perform the same actions using the event handler property, like this:

js
exampleSocket.onclose = (event) => {
  console.log("The connection has been closed successfully.");
};

Specifications

Specification
WebSockets Standard
# dom-websocket-onclose

Browser compatibility

BCD tables only load in the browser

See also