JSFiddle - React, Tailwind, and code Playground

HTML

<select class="liste" size="5">
    <option value="Minor">Minor</option>
    <option value="Single">Single</option>
    <option value="Married">Married</option>
    <option value="Divorced">Divorced</option>
    <option value="Widowed">Widowed</option>
</select>
<div id="absenden" style="display:none;">
    <input type="submit" value="senden" />
</div>

JavaScript

jQuery("select.liste option").mouseup(function () {
    var foo = $('select.liste option:selected').val();
    if (foo === "") {
        alert("nix ausgewählt");
    } else {
        alert(foo);
    }
});