JSFiddle - React, Tailwind, and code Playground

HTML

<div class="search-form search_inventory_box row  styled_input"><form method="get" action="#"><input type='hidden' name='page_id' value=''><div class="col-md-6 clearfix"><div class="my-dropdown make-dropdown make-dropdown"><select name='make' class='css-dropdowns' data-sort='make' data-prefix='' data-label-singular='Make' data-label-plural='Makes' data-no-options='No options'><option value=''>Make</option><option value='Nissan' data-key='nissan'>Nissan</option>
<option value='Porsche' data-key='porsche'>Porsche</option>
</select></div><div class="my-dropdown model-dropdown make-dropdown"><select name='model' class='css-dropdowns' data-sort='model' data-prefix='' data-label-singular='Model' data-label-plural='Models' data-no-options='No options'><option value=''>Model</option><option value='Boxster' data-key='boxster'>Boxster</option>
<option value='Carrera' data-key='carrera'>Carrera</option>
<option value='Cayenne' data-key='cayenne'>Cayenne</option>
<option value='GTR' data-key='gtr'>GTR</option>
<option value='GTS' data-key='gts'>GTS</option>
</select></div><div class="my-dropdown transmission-dropdown make-dropdown"><select name='transmission' class='css-dropdowns' data-sort='transmission' data-prefix='' data-label-singular='Transmission' data-label-plural='Transmissions' data-no-options='No options'><option value=''>Transmission</option><option value='5-Speed Automatic' data-key='5-speed-automatic'>5-Speed Automatic</option>
<option value='5-Speed Manual' data-key='5-speed-manual'>5-Speed Manual</option>
<option value='6-Speed Automatic' data-key='6-speed-automatic'>6-Speed Automatic</option>
<option value='6-Speed Manual' data-key='6-speed-manual'>6-Speed Manual</option>
<option value='6-Speed Manual|6-Speed Manual' data-key='6-speed-manual-6-speed-manual'>6-Speed Manual|6-Speed Manual</option>
<option value='6-Speed Semi-Auto' data-key='6-speed-semi-auto'>6-Speed Semi-Auto</option>
<option value='8-Speed Automatic' data-key='8-speed-automatic'>8-Speed...

JavaScript

$('.search_inventory_box form').submit(function(e) {
		console.log('fwef');
    
document.querySelector('.css-dropdowns').required = true;
    
		$('.search_inventory_box form select[value=""]').attr('name', '');

		$(this).find("select option:selected").each( function(index, element){
			$(this).val($(this).data('key'));
		});
	});