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

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

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

onclose = (event) => {};

A CloseEvent. Inherits from Event.

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.

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.

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:

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

• WebSocket: error event
• WebSocket: message event
• WebSocket: open event
• Writing WebSocket client applications