List with non selectable items

Yes is this! https://codepen.io/adrian-ortega/pen/Ivzjh
Thank you so much!

Can you help me where i can add the JS?

$(function(){
var foundin = $(‘#some_select option:contains(“optgroup-“)’);
$.each(foundin, function(value){
var updated = $(this).val().replace(‘optgroup-‘,”);
$(this).nextUntil(‘option:contains(“endoptgroup”)’).wrapAll(‘<optgroup label=”‘+updated+'”></optgroup>’);
});
$(‘#some_select option:contains(“optgroup-“)’).remove();
$(‘#some_select option:contains(“endoptgroup”)’).remove();
});