I have seen some best practices in WordPress about enqueueing scripts in WordPress. The scripts that are already in WordPress core should not be added again, but call that from WordPress core. I want to know whether select2 is in WordPress core. I have found only one article saying so
here
1 Answer
It’s not. They may have been planning it for 4.1 or 4.2, as suggested in your link, but for whatever reason it never happened.
You can see a list of core-registered scripts that you include here.
Another thing to keep in mind is that many (arguably too many) plugins enqueue their own version of the script, so be aware of potential conflicts.
