我似乎是浏览器特定的行为——firefox 立即显示数据(Hello:")，而 chrome 似乎在缓冲并等待响应结束.请注意，如果您一开始写入更多数据，chrome 也会立即显示数据(例如，我写了 1000 个Hello").

I seems to be browser specific behavior -- firefox shows the data ("Hello:") immediately while chrome seems to buffer and wait until the response is ended. Note that chrome also shows the data immediately if you write more data at first (e.g. I wrote 1000 "Hello"s).