JSFiddle - React, Tailwind, and code Playground

HTML

<dl>
    <dt><label for="typ">Typ</label></dt>
    <dd>
    <select id="typ" size="1">
        <option value="1" data-rel="norm">Normálna</option>
        <option value="0" data-rel="pres">Presmerovanie</option>
    </select>
    </dd>
</dl>
<!-- Len ak je presmerovatelna -->
<div id="pres" style="display: none;">
    <dl>
        <dt><label for="presmerovat">Presmerovat na</label></dt>
        <dd>
        <select id="presmerovat" size="1">
            <option>Category 1</option>
            <option>Category 2</option>
        </select>
        </dd>
    </dl>
</div>
<div id="norm" style="display: none;">
    <dl>
        <dt><label for="presmerovat">Normálnana</label></dt>
        <dd>
        <select id="presmerovat" size="1">
            <option>Category 1</option>
            <option>Category 2</option>
        </select>
        </dd>
    </dl>
</div>

JavaScript

$(document).ready(function() {
    $("#typ").on("change", function() {
        $(this).find("option").each(function() {
            var rel = $(this).data("rel"); 
            if (rel && rel.length > 0) {
                var obj = $("#" + rel);
                if ($(this).is(":selected"))
                    obj.show();
                else
                    obj.hide();
            }
        });
    });
    
    //show initial item:
    $("#typ").change();
});