JSFiddle - React, Tailwind, and code Playground

HTML

<select id="Box" size="6">
 <option value="R6">Yamaha R6</option>
 <option value="R1">Yamaha R1</option>
</select>
<input type="button" id="bouton_Envoyer" value="Send>>>" onclick="Send()">
<input type="button" id="bouton_Envoyer" value="Delete<<<">
<select id="Box2" size="6">
  <option></option>
</select>
    
<script>
function Send ()
{
    var x = document.getElementById("Box");
    var Select_value = x.options[x.selectedIndex].text;
     
     var newOpt = document.createElement('option');
     newOpt.innerHTML = Select_value;
     document.getElementById('Box2').appendChild(newOpt);
}
</script>