JSFiddle - React, Tailwind, and code Playground

HTML

<script>
var dropboxOpen = false,
    oldItem     = null;
function onClick(e) {
    if (dropboxOpen) {
        if (oldItem && oldItem === e.target.value) {
            console.log('same selected');
        }
        oldItem = e.target.value;   
    }        
    dropboxOpen = !dropboxOpen;
}

    
</script>

<select onclick="onClick(event)">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="opel">Opel</option>
  <option value="audi">Audi</option>
</select>