JSFiddle - React, Tailwind, and code Playground

HTML

<div id="selection">
    <label>Label1:</label>
    <select class="select">
        <option value="1">V1</option>
        <option value="2">V2</option>
        <option value="3">V3</option>
    </select>
    <label>Label2:</label>
    <select class="select">
        <option value="4">U1</option>
        <option value="5">U2</option>
        <option value="6">U3</option>
    </select>
</div>

JavaScript

var num = 3;
$("div#selection select.select option[value="+num+"]").prop("selected", true);