CollectionBinder: don't sort elements on 'add' event

[amakhrov]

Backbone triggers 'sort' each time an model was added to the collection if it changed the sort order. So there is no point in sorting dom elements on 'add' event - doing that on 'sort' would be enough.

What's more, it leads to broken collection rendering on collection.set, as sortRootEls is called after each individual add event is triggered - at this point the collection has the full set of models, but only some of them have been rendered. One of the added unit tests fails with the original code due to that.

[platinumazure]

What about collection.add(model, { at: 0 })? Wouldn't that possibly result in an inconsistent ordering between the collection and the DOM?

[amakhrov]

Good point! However, I believe for this case createEl method should be implemented in a way that it inserts the newly added element straight into the right place in DOM instead of appending and then re-sorting everything.

[platinumazure]

@amakhrov Good call, I agree. No reason options.at couldn't be made available there. I look forward to the tweaks :-)

EDIT: On second thought, that's really a separate issue. I'll go start that one.

[amakhrov]

@platinumazure all the feedback is incorporated:

• add unit tests
• fix the behavior with {at: 0} . It's not really a separate issue, as it only occurs after my original commit.

[platinumazure]

@theironcook This should be safe to merge.

[theironcook]

Merged. I hope it works :)