Minor fixes to new media bindings

[martinandert]

Thanks for merging #819, even though it wasn't perfect! Here are a two small fixes to things I've noticed when looking at d75ab85 or when playing around with the new release.

[Rich-Harris]

Thanks, good catch on the logical expression. I don't understand why we need the if (!ranges) guard?

[Rich-Harris]

when could this be the case?

[martinandert]

Because the src attribute may not be present and then all the ranges attributes return undefined.

[martinandert]

https://svelte.technology/repl?version=1.39.0&gist=66b93597de37579256dc333177c56e96

I could wrap the #each in an #if, but I don't really like to do that.

And since the method name is suffixed with ToArray, I somehow expect it to always return an array, regardless of the input.

[Rich-Harris]

In what browsers is that true? In Chrome:

Fairly certain that's spec.

[Rich-Harris]

I think what's happening here is we need to initialise the bindings to an empty array — adding the guard to this function probably won't fix it

[martinandert]

we need to initialise the bindings to an empty array

Ah ok, I can do that.

[martinandert]

I think what's happening here is we need to initialise the bindings to an empty array

Done in bfaab99. Though I'm not entirely sure this is better. Judging from your screenshot, how can audio.buffered not return a TimeRanges instance in the first place?

[Rich-Harris]

That's not quite what I meant — the binding needs to be initialised, i.e. the value of played needs to be set to an empty array immediately. Unfortunately that's slightly tricky as things stand, and will require some additional work (though that work will have benefits in other places), which I'll create a new issue for. Apologies for the confusion, I didn't immediately realise this wasn't possible.

The workaround in the meantime is to initialise the value manually (note the "played": [] in the bottom right).

I cherry-picked the first commit into #841, so I'll close this. Thanks.