How can I update dropdown item with new content after selection?

How Do I...
#1

I want click on dropdown item and add number to it after that. And name in selection place has to be changed too.

For example I want to change “Moscow” to “Moscow (2)” after click.
изображение

I could do it changing “select2-container” with JQuery directly without adapters. I detected events ‘select’ and ‘unselect’, got “select2-container” and changed text for select2-results__option.

How can I do it more correct?

#2

Use a custom result template callback to append the number based on whatever criteria you need.