Value of the Service-Worker request header

[Nowasky]

Is it up to browsers to decide what value will be included in the Service-Worker request header when an HTTP request is made to fetch a service worker's script resource?

I've noted that some browsers use script as the value for this header, but I couldn't find this information in the spec.

I'm unsure if administrators should be looking for the Service-Worker: script header specifically to detect the registration of a service worker.

[Nowasky]

Turns out it is in the spec. I don't know how I missed that.

Append `Service-Worker`/`script` to request’s header list.

https://w3c.github.io/ServiceWorker/#update-algorithm

Anyway, is it safe to assume that a registration request will always use script as the header's value? Or it's safer to check for the presence of the header regardless of its value?

[wanderview]

We've thought about using a value of module if its a module service worker, but AFAIK no one is doing that yet. See:

#1582 (comment)