JSFiddle - React, Tailwind, and code Playground

HTML

<select name="category">
    <option value="A">A</option>
    <option value="B">B</option>
    <option value="C">C</option>
</select>

<input id="auto" data-id="A" type="search"/>

JavaScript

$('#auto').autocomplete({
    delay: 100,
    source: function( request, response ) {  
        var selected = $('select[name="category"] option:selected'),
        	isSomethingSelected = selected.length == 1,
            selectedVal = isSomethingSelected ? 
            			  selected.val() :
                          $('select[name="category"] option:first').val();
        
        alert(selectedVal);
        return false;
    }
 });