Uniquify multiple headers of the same name or something?

[BobbyWibowo]

Hi there,

Suppose I want to have a global middleware that sets a specific Cache-Control header for all requests (thus acting like a default value), but then down the line some more specific routes may set their own Cache-Control headers, how would I go about achieving those routes to only end up with the last set Cache-Control header?

From what I can tell, it was intentional to allow multiple headers of the same name (?)

hyper-express/src/components/http/Response.js

Lines 172 to 173 in fb447d1

	// Initialize header values as an array to allow for multiple values
	if (this.#headers[name] == undefined) this.#headers[name] = [];

ExpressJS, at least v4.x, will only keep the last set one, so this is a bit of an unexpected behavior for me

[kartikk221]

I'm not sure If I fully understand the expected behavior from your post. If the header() call was to use the last set value of a header (essentially replacing/ignoring previous values) then how would multiple middlewares be able to write multiple cookies with the set-cookie header during the lifetime of a request?

[BobbyWibowo]

From what I can tell, as of Express v4.18.1, it would only allow multiple Set-Cookie headers if set via res.cookie() function
Otherwise if set via res.set() or res.header(), it would only keep the last value, even if it is Set-Cookie header

Assume the following code snippets:

res.set('Cache-Control', 'no-cache')
res.set('Cache-Control', 'test1')
res.set('Cache-Control', 'test2')
res.set('Cache-Control', 'test3')
res.cookie('name', 'tobi')
res.cookie('rememberme', '1')

ExpressJS would end up with the following:

Meanwhile Hyper-Express:

Then suppose down the line there is the following snippet:

res.set('Set-Cookie', 'who is tobi')

ExpressJS would then simply end up being:

[kartikk221]

Thanks for the breakdown. This issue has been fixed in the recent v6.2.5 release. Hope that helps!

[BobbyWibowo]

Awesome! Tyvm!