Node.js请求管道终止响应

Question

I have this nodejs code but to be honeste I can't quite understand what .pipe does.

var localoptions = {
  url:  requestUrl,
  milliseconds, default is 2 seconds
};


if (authHeader) {
  localoptions.headers = {
    "Authorization": authHeader
  };
}

request(localoptions)
.on('error', function(e) {
 res.end(e);
}).pipe(res);

res in this case is the response from a function that handles a specific route.

Does .pipe in this case end the res response with the response it gets?

Answer 1

If you pipe to a stream then the destination will be closed as soon as the source ends (expect if you pass an end callback as option)

readable.pipe(destination[, options]) :

options <Object> Pipe options
end <Boolean> End the writer when the reader ends. Defaults to true .

And here the corresponding part in the source node: stream.js

// If the 'end' option is not supplied, dest.end() will be called when
// source gets the 'end' or 'close' events.  Only dest.end() once.
if (!dest._isStdio && (!options || options.end !== false)) {
   source.on('end', onend);
   source.on('close', onclose);
}

var didOnEnd = false;
function onend() {
   if (didOnEnd) return;
   didOnEnd = true;

   dest.end();
}