流 (stream)

‘finish’ 与 ‘end’ 事件的区别

node 官方文档：

The ‘finish’ and ‘end’ events are from the stream.Writable and stream.Readable classes, respectively. The ‘finish’ event is emitted after stream.end() is called and all chunks have been processed by stream._transform(). The ‘end’ event is emitted after all data has been output, which occurs after the callback in transform._flush() has been called.

https://nodejs.org/api/stream.html#stream_events_finish_and_end

stackoverflow 解答：

end and finish are the same event BUT on different types of Streams.

• stream.Readable fires ONLY end and NEVER finish
• stream.Writable fires ONLY finish and NEVER end

Source: https://nodejs.org/dist/latest-v5.x/docs/api/stream.html

Why the different naming of the same event?

The only reason I could think of is because of duplex streams (stream.Duplex), which implement both stream.Readable and stream.Writable interfaces (https://nodejs.org/dist/latest-v5.x/docs/api/stream.html#stream_class_stream_duplex) are readable and writable stream at the same time. To differentiate between end of reading and end of writing on the stream you must have a different event fired. SO, for Duplex streams end is end of reading and finish is end of writing.

https://stackoverflow.com/a/34310963