JSFiddle - React, Tailwind, and code Playground
HTML
<select multiple="multiple" id="multiple">
<option value="1">item 1</option>
<option value="2">item 2</option>
</select>
JavaScript
$('#multiple').val(['1', '2']);
<select multiple="multiple" id="multiple">
<option value="1">item 1</option>
<option value="2">item 2</option>
</select>
$('#multiple').val(['1', '2']);