HTML5 websocket的headr如何加入扩展参数

HTML5 websocket的headr如何加入扩展参数：如下：
websocket = new WebSocket("ws://192.168.152.73:8099");

WebSocket {}
binaryType: "blob"
bufferedAmount: 0
extensions: ""
onclose: null
onerror: null
onmessage: null
onopen: null
protocol: ""
readyState: 1
url: "ws://192.168.152.73:8099/"
proto: WebSocket

https://github.com/websockets/ws/blob/master/doc/ws.md#websocketupgradereq
options里面加headers