JSFiddle - React, Tailwind, and code Playground

HTML

<form id="form">
<select class="certain-class">
  <option value="false">Volvo</option>
  <option value="true">Saab</option>
</select>
<input type="submit" value="Submit">
</form>

CSS

/*
RESETS ------------------------------------------------------------
*/ 

html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, font, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td {margin: 0;padding: 0;border: 0;outline: 0;font-size: 100%;vertical-align: ;background: transparent;}

.wrap {
    position: relative; 
    width: 100%; height: auto;
}

.test {
    display: inline-block;
    margin: 10px;
    width: 100px;
    height: 100px;
    display: none;
}

JavaScript

$( document ).ready(function() {
    $( "#form" ).submit(function(event) {
        $(".certain-class").val("true");
        alert("test");
    })
});