JSFiddle - React, Tailwind, and code Playground

HTML

<select class="dropdown">
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
</select>
<select class="dropdown2">
</select>

JavaScript

var dropdown2 = {
    1 : ['Four', 'Five', 'Six'],
    2 : ['Seven', 'Eight', 'Nine'],
    3 : ['Ten', 'Eleven', 'Twelve']
}
$('.dropdown').on('change',function() {
    $('.dropdown2').html(
      '<option>'+dropdown2[$(this).val()].join('</option><option>')+'</option>'
    );
});