Question - select default option in the selectbox

[githubGabriela]

How do you select a default option in the select box?
Let's say you use this select box inside a form and when you want to edit the form the value Antarctica must appear already selected in the select box.

One possible solution would be this:
// set value
$("#my_select2_element").select2("val", "Antarctica");

This solution works with a select box static e.g.:

Asia Antarctica

but will not work if the options are created inside a template dom-repeat because every option is inside a template.

Another solution will be this:

{{item.label}}

but this will select a value inside the select list options. Still, there will be no value preselected in the select box.

How would you preselect a value in the select box?

Thankx!