JSFiddle - React, Tailwind, and code Playground

by GaryC123

HTML

<select id="ListBox2" onchange="ListBox2_onchange(this)">
    <option>1</option>
    <option>2</option>
    <option>3</option>
</select>

<script>
    function ListBox2_onchange(listBox2)
 {
    alert(listBox2.options.length)
  var DropDownList1 = document.getElementById('DropDownList1');
 
 for (var i=0; i<listBox2.options.length; i++)
  {
   if ( listBox2.options[i].selected )
   { 
    var newOption = window.document.createElement('OPTION');
    newOption.text = listBox2.options[i].text;
    newOption.value = listBox2.options[i].value;
 
   DropDownList1.options.add(newOption);
    listBox2.options.remove(i);
   }
  }
  
  persistOptionsList();
 }
</script>