In easyadmin we can use the pretty cool Tomselect library in an entity crud form https://symfony.com/doc/current/EasyAdminBundle/fields/AssociationField.html
But how can I use this library in a filter?
If you want to use tomselect in a layout from easy admin (which then include easy admin javascript), you can define a select as a tomselect widget.
Just add html attribute data-ea-widget="ea-autocomplete"
on your select and it should become a tom select. This is done automatically when using a select in a form but nothing prevent you from doing it manually.
Or if you are using webpack, you could just import TomSelect and use it.
import TomSelect from 'tom-select'
new TomSelect('#select_id')