Correct headers, but Chrome says "Resource interpreted as Document"

Question

I read a lot of questions like this one, but I really can't figure it out...

I use the archiver and express Node.js modules. I want to simply send a zip file to the client. My code looks roughly like this:

res.set("Content-Type", "application/zip");
archive = archiver("zip", {store: true});
archive.pipe(res);

When requested, the zip file is transferred correctly, but Chrome complains:

Resource interpreted as Document but transferred with MIME type application/zip

If I do something stupid like setting the content type to text/json, I get:

Resource interpreted as Document but transferred with MIME type text/json

So apparently what I'm setting in Node.js is doing its job and something else is the problem. It says the resource was transferred with MIME type applicatioin/zip, but interpreted as Document.

How do I make it not interpret as Document?

---

Also, I tried these ways of setting the content type:

res.type("application/zip");
res.contentType("application/zip");

But I got the same result.

Mozilla, on the other hand, doesn't complain about anything. Some answers to similar questions said this warning can be ignored. Should I ignore it too? Could the problem be that the archive is piping directly to the response object? Although (I repeat), the zip is sent successfully.

Edit:

Setting Content-Disposition doesn't work too:

res.set({
    "Content-Type": "application/zip",
    "Content-Disposition": "attachment; filename='images.zip'"
});

I also use an <iframe> to initiate the request:

document.getElementById("iframe-downloader").src = requestUrl;

The reason is because I don't want page redirects. The only way I could manage to do it was this way.

Edit:

Changing my Chrome settings how this answer points out doesn't work as well.

Edit:

This answer says it's because of the <iframe>. If I make the request through a simple <form> with action="/archive", it still doesn't work.

Answer 1

I think that means Chrome is trying to display the file as a webpage, which is not what you wanted.

Add the header: Content-Disposition: attachment; filename="filename.ext"