How to detect client (pushState) routing in loader?

[maranomynet]

What is the best way to differentiate between client-routed requests and normal browser/curl requests, within loader (and action)?

Is this even supported?

• I notice that loader seems to receive a request with the ?_data= parameter stripped from the URL.

• I know it's possible to hijack/overload the global fetch method, but that feels like an act of desperatation.

Rationale:

I've been thinking of ways to use defer but mitigate the issue of HTML arriving out of order, depending on JavaScript to eventually reach correct form.

On initial/full page loads (via outside links, or browser page refresh) I'd like to await all the promises and return an orderly rendered HTML page.

However, when users navigate between pages via Remix's client-side routing, I'd like to return defered loader data to do instantaneous transition the new UI in a loading state (I know, ick spinners, but hey), and then re-render when the data arrives.

[Markyiptw]

#5084 seems to be a viable solution.

[maranomynet]

Thank you!
Yes, checking the Accept header sounds sufficiently "clean" for my taste.

[maranomynet]

Actually it turns out the Sec-Fetch-Dest header is the way to go. See this comment from @sergiodxa