JAVASCRIPT

select2 get selected value

//get all selected select object
$('#select2Id').find(':selected');

//get all selected value 
$("#select2Id").select2("val");

get select2 selected value jquery

$('#id :selected').text();

select2 find option by value

$('#Select2ID option[value="actualVal"]).text()

select2 multi select get selected value

alert("Selected value is: "+$(".leaderMultiSelctdropdown").select2("val"));

alternatively, if you used a regular selectbox as base, you should be able to
use the normal jquery call, too:

alert("Selected value is: "+$(".leaderMultiSelctdropdown").val());