Apparently, there are like 5 independently developed jquery-caret
plugins, none of which are great. The previous one we were using was
last modified in 2010. This new one comes from
https://github.com/acdvorak/jquery.caret and at least doesn't use
deprecated jQuery syntax and has a repository on GitHub.
This plugin is way larger than it needs to be for what it does, but we
can deal with that later.