Fixes #1038 - Document changes to view.$.

[braddunbar]

No description provided.

[jashkenas]

I don't know if this is necessary -- there's no conceivable reason to ever do that, or to have ever been doing it in the past. Why do we need to call it out?

[akavlie]

I ran into this; it was the main gotcha with upgrading Backbone 0.9. Our main view was using a template as view.el, and that worked fine in Backbone 0.5.3 (even if not intended). Eventually figured out what was going on by looking at the code, but a mention in the upgrade notes would have helped.

[braddunbar]

It's equivalent to running: $(selector, this.el)

I don't think there is any question that the documentation above should change since it's patently false. As for the upgrade notes, there are certainly legitimate situations in which the previous behavior is very convenient. For instance:

var el = this.$(foo ? selector : htmlstring);

Obviously this could have been written differently but for what reason? The documentation spells out very clearly that it will work just fine.

[jashkenas]

If it's convenient in real-world code -- why don't we just go back to the previous behavior?

[braddunbar]

The reason for the change was performance and a comparison shows that it can be 15-30% faster, and never slower. Is this enough to justify the change in API? I think it's a fairly easy thing to fix for a clear performance win. However, I don't have a strong opinion either way except that the change should be documented if the implementation is left as is.

[jashkenas]

Ok -- I'll relent ;)