doc(http): res.write(data) followed by res.end() is not actually equivalent to res.end(data)

[peat-psuwit]

• Version: v11.9.0
• Platform: Linux (My hostname) 4.15.0-45-generic #48-Ubuntu SMP Tue Jan 29 16:28:13 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux (Xubuntu 18.04)
• Subsystem: Documentation of HTTP module

In the document for method end([data][, encoding][, callback]) of class http.ServerResponse, there's a following text:

If data is specified, it is equivalent to calling response.write(data, encoding) followed by response.end(callback).

However, this is not actually true when there's only single response.write(data), demonstrable with the following code:

const http = require('http');

const HELLO = 'Hello!\n';

const server1 = http.createServer(function (req, res) {
  res.write(HELLO);
  res.end();
});

const server2 = http.createServer(function (req, res) {
  res.end(HELLO);
});

server1.listen(9001);
server2.listen(9002);

By using curl -v, this happens:

$ curl -v http://localhost:9001/ # response.write(data) follow by response.end()
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 9001 (#0)
> GET / HTTP/1.1
> Host: localhost:9001
> User-Agent: curl/7.58.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< Date: Fri, 08 Feb 2019 10:26:25 GMT
< Connection: keep-alive
< Transfer-Encoding: chunked
< 
Hello!
* Connection #0 to host localhost left intact

$ curl -v http://localhost:9002/ # response.end(data)
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 9002 (#0)
> GET / HTTP/1.1
> Host: localhost:9002
> User-Agent: curl/7.58.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< Date: Fri, 08 Feb 2019 10:26:31 GMT
< Connection: keep-alive
< Content-Length: 7
< 
Hello!
* Connection #0 to host localhost left intact
$ 

So, it appears that response.write(data) follow by response.end() cause Node.js to use chunked encoding, while response.end(data) cause Node.js to not using chunked encoding and include Content-Length header. This small distinction is important with some client. For example, Windows 10's MDM enrollment system will not accept chunked response.

[lpinca]

@peat-psuwit are you interested in submitting a PR to fix the documentation?

[peat-psuwit]

Hmm, I'm not sure how I should change the document. Also, after I read some comment in the source I start to wonder if the current behavior is not an intended behavior.

[lpinca]

I think current behavior is intended, but the sentence you quoted is misleading. Perhaps remove it or reword it to match current behavior?

cc: @nodejs/http

[lpinca]

Current behavior was defined in #1062. Before that both cases in your example returned Transfer-Encoding: chunked.