The API is a little confusing because animate returns a reference to the element to enable chaining.
But you can do this:

$element.animate(...);
$element.promise().then(function() { ... });

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

jQuery: Get a promise for the end of an animation