Get selected value of a dropdown's item using jQuery

Question

How can I get the selected value of a dropdown box using jQuery?
I tried using

var value = $(\'#dropDownId\').val();

and

Answer 1

I know this is old but I though I update this with an more up to date answer

$( document ).on( 'change', '#combo', function () {
var prepMin= $("#combo option:selected").val();
 alert(prepMin);
});

I hope this helps