feat(link): prefetch symbols

[wmertens]

rebase of #4678

@jordanw66 does this look ok?

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[wmertens]

@mhevery any idea what this error could be? https://app.netlify.com/sites/qwik-insights/deploys/65630257f2395100085905ed#L346

[wmertens]

@jordanw66 actually, shouldn't these include the given props if any (if so, that's an existing bug)?

And I don't understand why the handling happens only when isDev?

[jordanw66]

Perhaps it's an existing bug for Link, but not dire because you can always put those on projected children.

For prefetch, the doc comment at the bottom of that file on the prefetch attribute explains the logic behind it:

Basically Next prefetchs Links by default when they become visible. In Dev mode this would be a waste and pointless, but also not having anything happen would probably lead some people to question whether it's working.

So I split the difference: in prod it works like normal (!isDev on visible only), in Dev mode it only does it on mouseover or focus. This keeps it kind of similar to current behavior which already does prefetch in Dev mode anyway.

If you feel this behavior is incorrect it's no problem it's a small change to fix, just a DX decision I made at the time.

[jordanw66]

Looks good to me, I would also consider fixing this existing prefetch issue if you can:

#5474

It's probably a quick one or two line fix, I left a comment explaining what the issue probably is but don't have time to test it.

[mhevery]

You are assuming that all paths end with / This is the default but it is possible to configure Qwik without trailing slash.

[jordanw66]

Yes that's true but the purpose of this line is entirely internal to this function. It normalizes all potential paths it receives from the Link href before adding it to the list of prefetched paths.

And the reason for this is so that if, for whatever reason, someone has two Links:

href="/todo/" and href="/todo"

The symbols for these paths are the same and it won't dispatch a symbol prefetch twice.

[maiieul]

This should also fix #5240 (a.k.a SPA prefetch on mobile), right?

[jordanw66]

This should also fix #5240 (a.k.a SPA prefetch on mobile), right?

Don't think so, this still uses onQVisible. It just modifies the behavior of Link to match Next: prefetch by default, on visible, on both mobile and desktop, opt-out with false or optionally prefetch js bundles only with "js". This behavior that Next uses makes much more sense since it's kind of what you want by default anyway if you're doing SPA with Link. It also adds some optimizations to Link reducing handlers and not prefetching on same-page & hashes, etc.

onQVisible is set up by the Qwik loader on page load IIRC and isn't re-done on navigates I assume so that's a separate issue that would need to be addressed in a different PR