Expose response headers which are currently set.

[JvJefke]

I have a use case where I need a list of all currently set headers. This is possible with the unofficial res._headers property. It would be great if there would be an official way to get this information.

Maybe the response object could be extended with this:
res.getHeaders();

This would then return a copy of the currently set headers.

Does this seem like a good idea?

[dougwilson]

Yea, it was added in Node.js 7.7.0: https://nodejs.org/dist/latest-v8.x/docs/api/http.html#http_response_getheaders

[JvJefke]

Oh ok. I didn't know that.
Sadly we are stuck with supporting 4.x.x and up so this is not a solution for us.
I can however make our implementation future proof by checking the availability of this new function before using res._headers.

Thx for the quick response!

[dougwilson]

Yea, we don't shadow or shim APIs in Express.js, just the additional sugar that is needed. nodejs/node#10805 is the PR in Node.js and it's been requested to be backported to Node.js 6.x multiple times, I think you can request it be backported to 4.x as well, though.