How to get headers only?

[gajus]

I want to make a request, read headers, follow redirects if such occur, but do not download the body.

The use case is to expand shortened URLs.

Sometimes shortened URLs can link to large files.

I guess this requires a resolveHeadersOnly option.

[sindresorhus]

Can you do a HEAD request? That would not fetch the body.

[gajus]

That was the first thing I tried.

Unfortunately, some URLs return "Method Not Allowed" when you do HEAD request, e.g. any http://gcr.io/ URLs.

[gajus]

It is fine if whatever the approach would download some of the body. I just want to make sure that I don't end up downloading some random 1GB zip files.

[szmarczak]

got.stream('http://gcr.io/').on('response', response => {
    console.log(response.headers);
}).resume();

It will download the file, but will not save it. It's gonna be removed immediately.

[gajus]

Good suggestion, but unfortunately this would be a huge waste of bandwidth, esp. at a scale that I am doing this.

[szmarczak]

unfortunately this would be a huge waste of bandwidth

So you do not want do download data. In other words you don't want to keep the connection, that means you want to cancel the request:

const getHeaders = () => new Promise((resolve, reject) => {
    const promise = got('http://gcr.io/').on('response', response => {
        resolve(response.headers);
        promise.cancel();
    });
    
    promise.then(response => resolve(response.headers)).catch(reject);
});

(async () => {
    console.log(await getHeaders());
})();

Note that you need to cancel ONLY when you're not being redirected, because you will break the chain otherwise.

I hope this solves your problem :)