stream.onheaders

• 类型：<Function>

当在流上接收到初始头时要调用的回调。回调接收 (headers)，其中 headers 是一个对象（格式与 stream.headers 相同）。对于 HTTP/3，这在服务器端提供请求伪头，在客户端提供响应头。如果在不支持头的会话上设置，则抛出 ERR_INVALID_STATE。可读/可写。

🌐 The callback to invoke when initial headers are received on the stream. The callback receives (headers) where headers is an object (same format as stream.headers). For HTTP/3, this delivers request pseudo-headers on the server side and response headers on the client side. Throws ERR_INVALID_STATE if set on a session that does not support headers. Read/write.