When using Client-Side Object Model for SharePoint 2013, how can I access previous versions of List Item?
If you have a document library use:
However if you have a normal list this won't work, but instead you can request the item file directly. This is a hack and I can't guarantee future support:
You can also use SPServices although I'm not sure this will work with CORS.
According to this article
should provide the collection you are looking for.
Be careful: SPListItem.Versions and SPListItem.File.Versions are different.