How to attach additional data when using hooks

[makbol]

Hi! 👋

I would like to measure the duration of HTTP requests — from the moment they are initiated to the point the Response is received (excluding .json() parsing). The goal is to include this metadata (e.g. duration) in a way that can be accessed later, ideally without breaking the native Response API or Ky’s clean structure.

I’ve explored several approaches — attaching timestamps to options in beforeRequest, wrapping Ky methods, reconstructing Response objects, or returning custom { data, duration } shapes — but none of them provide a clean, reliable solution that maintains type safety, Ky compatibility, and performance.

As an example of the problem, consider this setup:

const api = ky.create({
  hooks: {
    beforeRequest: [
      (_request, options) => {
        options._start = performance.now();
      }
    ],
    afterResponse: [
      (_request, options, response) => {
        const start = options._start;
        const duration = start ? performance.now() - start : undefined;
    
        // But now what? There's no safe or standard place to store `duration`
        // - Mutating the response (e.g. `response.duration = ...`) feels wrong
        // - Replacing the response with a custom object breaks compatibility
        // - Wrapping all calls loses Ky's chaining and hook benefits
    
        return response;
      }
    ]
  }
});

Related

I found #329, which discusses accurate request timing, but my use case is more lightweight — I just want a rough request duration for basic monitoring/logging.

My question

Is there an officially supported or idiomatic way to propagate lightweight metadata like duration across Ky’s lifecycle — from beforeRequest to afterResponse, and ideally to the consumer?
If not, would you consider exposing a context or metadata mechanism to enable this kind of need?

Thanks again for maintaining Ky — it’s a fantastic library and I’d love to keep using it in a clean and maintainable way.

[sindresorhus]

I think #677 is what you want.