Does fetch() support upgrading the connection to a websocket?

What happens when

fetch()

fetch()

gets the response

HTTP/1.1 101 Switching Protocols
connection: upgrade
upgrade: websocket

HTTP/1.1 101 Switching Protocols
connection: upgrade
upgrade: websocket

HTTP/1.1 101 Switching Protocols
connection: upgrade
upgrade: websocket

HTTP/1.1 101 Switching Protocols
connection: upgrade
upgrade: websocket

…? How to get the

WebSocket

WebSocket

WebSocket

WebSocket object from there?