JSFiddle - React, Tailwind, and code Playground

HTML

<select multiple="multiple" size="2">
    <option>1</option>
    <option>2</option>
</select>
<div></div>

<select>
    <option>1</option>
    <option>2</option>
</select>
<div></div>

JavaScript

$('div').each(function() {
    var options = $(this).prev();
    options.find('option').attr('selected', 'selected');
});