'continue' 事件
当服务器发送 100 Continue
状态时触发,通常是因为请求包含 Expect: 100-continue
。
这是客户端应该发送请求正文的指令。
Emitted when the server sends a 100 Continue
status, usually because
the request contained Expect: 100-continue
. This is an instruction that
the client should send the request body.