Use express sendFile for HEAD requests - node.js

Question

sendFile is for sending files and it also figures out some interesting headers from the file (like content length). For a HEAD request I would ideally want the exact same headers but just skip the body.
There doesn't seem to be an option for this in the API. Maybe I can override something in the response object to stop it from sending anything?
Here's what I got:
res.sendFile(file, { headers: hdrs, lastModified: false, etag: false })
Has anyone solved this?

Answer 1

As Robert Klep has already written, the sendFile already has the required behavior of sending the headers and not sending the body if the request method is HEAD.
In addition to that, Express already handles HEAD requests for routes that have GET handlers defined. So you don't even need to define any HEAD handler explicitly.
Example:
let app = require('express')();
let file = __filename;
let hdrs = {'X-Custom-Header': '123'};
app.get('/file', (req, res) => {
res.sendFile(file, { headers: hdrs, lastModified: false, etag: false });
});
app.listen(3322, () => console.log('Listening on 3322'));
This sends its own source code on GET /file as can be demonstrated with:
$ curl -v -X GET localhost:3322/file
* Hostname was NOT found in DNS cache
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 3322 (#0)
> GET /file HTTP/1.1
> User-Agent: curl/7.35.0
> Host: localhost:3322
> Accept: */*
>
< HTTP/1.1 200 OK
< X-Powered-By: Express
< X-Custom-Header: 123
< Accept-Ranges: bytes
< Cache-Control: public, max-age=0
< Content-Type: application/javascript
< Content-Length: 267
< Date: Tue, 11 Apr 2017 10:45:36 GMT
< Connection: keep-alive
<
[...]
The [...] is the body that was not included here.
Without adding any new handler this will also work:
$ curl -v -X HEAD localhost:3322/file
* Hostname was NOT found in DNS cache
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 3322 (#0)
> HEAD /file HTTP/1.1
> User-Agent: curl/7.35.0
> Host: localhost:3322
> Accept: */*
>
< HTTP/1.1 200 OK
< X-Powered-By: Express
< X-Custom-Header: 123
< Accept-Ranges: bytes
< Cache-Control: public, max-age=0
< Content-Type: application/javascript
< Content-Length: 267
< Date: Tue, 11 Apr 2017 10:46:29 GMT
< Connection: keep-alive
<
This is the same but with no body.

Answer 2

Express uses send to implement sendFile, which already does exactly what you want.