Update castv2-sender.js

[jparthum]

I got to playing around and made some changes you may want to review:

• Line 81 corrects first array object [0] from being skipped.
• Lines 136-141 (notes) may be useful for future 'array-friendly' features.
• All following lines add metadata features. I've only tested MusicTrackMediaMetadata so far.

Hope this is helpful.

[i8beef]

So I incorporated the index change in the latest version... Im not sure on the rest. I think it has merit for sure, but I'm not that familiar with the cast API metadata rules, so before I go merging this I wanna read up on it a bit and see if I should do something like only including the RIGHT metadata elements when they apply (i.e., by that metadataType) instead of always supplying but leaving null, etc. Ill try and spend some time reading this weekend on it.

[jparthum]

I started to make two different PRs -- and in hindsight I probably should have. I'm not very familiar with PRs (or any other aspect of code publishing for that matter), so I wasn't sure what would be easier for you and/or better facilitate testing.

I considered including only those metadata elements applicable to the current stream but foresaw a couple of potential issues. Either:

• The syntax for the existing metadata object would need to be completely altered in order to provide naming consistency (eg: msg.payload.media.movieTitle, msg.payload.media.albumTitle, etc.), which would be a breaking change.

Or:

• The object keys that are shared between the metadata elements would need to be duplicated within the .js (eg: metadata: {metadataType: 1, title: XXX}, metadata: {metadataType: 3, title: YYY}, etc.), which would seem confusing to end-users and prone to mistake.

I tried the structure as submitted without much confidence that it would actually work, but so far it's been fine in my limited testing. I've been casting daily without issue, but only populating MusicTrackMediaMetadata.
Over the weekend I'll also try casting some Movies and TV shows and report back...

[i8beef]

So if the intention is to expose all of these options. Instead, I have put in an option to allow you to pass your own metadata object that will OVERRIDE the default when needed. This means I've deprecated the 'title' and 'image' properties entirely, in favor of just letting you pass them in the metadata override. As this brings in all the changes you intended here, I'm closing this in favor of the version I just pushed, 2.0.1. See if that works for you, and if not, please open a ticket.

[jparthum]

That's a great idea. I think the number of use-cases for this additional metadata are fairly small right now -- particularly beyond audio casts. Setting metadata.metadataType to anything except 0 effectively invokes 'advanced mode', allowing additional (IE: 'advanced') metadata entries that conform directly to Google's Media namespace data structures... that's brilliant!