JSFiddle - React, Tailwind, and code Playground

HTML

<form>
  <select name="single">
    <option>Single</option>
    <option>Single2</option>
  </select>

  <select name="multiple" multiple="multiple">
    <optgroup label='सत्यनारायण पूजा' id="1">
            <option value='1'>१. अबिर - &#189; kg </option>
            <option value='2'>२. केशरी</option>
            <option value='3'>२. शिवजीको लागि धोती - १</option>
          </optgroup>
          <optgroup label='ग्रहशान्ति पूजा' id="2">
            <option value='4'>Palpatine</option>
            <option value='5'>Darth Vader</option>
          </optgroup>
  </select>
</form>
<br><br><br>
<div id="results"></div>

JavaScript

function showValues() {
    var str = $( "form" ).serialize();
    //$( "#results" ).text( JSON.stringify(str) );
    alert(str);
  }
  $( "select" ).on( "change", showValues );
  showValues();