How to get selected simple product id in the configurable product from the dropdown options in Magento 2

Question

How to get selected simple product id in the configurable product from the dropdown options in Magento 2

The below code works fine with "Swatch Option" but not work with the "Dropdown Option"

  requirejs(['jquery','underscore'], function(jQuery,_){
        jQuery(window).load(function(){
            jQuery( ".product-options-wrapper div" ).click(function() {
                selpro();
            });
        });
        function selpro () {
            var selected_options = {};
            jQuery('div.swatch-attribute').each(function(k,v){
                var attribute_id    = jQuery(v).attr('data-attribute-id');
                var option_selected = jQuery(v).attr('data-option-selected');
                //console.log(attribute_id, option_selected);
                if(!attribute_id || !option_selected){ return;}
                selected_options[attribute_id] = option_selected;
            });
    
            var product_id_index = jQuery('[data-role=swatch-options]').data('mageSwatchRenderer').options.jsonConfig.index;
            var found_ids = [];
            jQuery.each(product_id_index, function(product_id,attributes){
                var productIsSelected = function(attributes, selected_options){
                    return _.isEqual(attributes, selected_options);
                }
                if(productIsSelected(attributes, selected_options)){
                    found_ids.push(product_id);
                } 
            });
            console.log(found_ids);
        }
    });

Answer 1

The below code works for the "Dropdown" Option.

<script type="text/javascript">
require(['jquery','underscore'], function(jQuery,_){
    var confProductId = jQuery('.price-box').attr('data-product-id');
    jQuery(".product-options-wrapper select[id^='attribute']").last().on('change', function() {
      setTimeout(function (){
        simpleId=jQuery("input[name=selected_configurable_option]").val();
        alert(simpleId);
    
        var data = [];
        var $el=jQuery(".product-options-wrapper select[id^='attribute']");
        $el.each(function(){
            data.push(jQuery(this).attr('id').replace('attribute', ''));
       });
       // do your stuff here
       }, 500); 
    });
});
</script>