JavaScript: add/remove body class (toggle) with checkbox

Markup

<input type="checkbox" id="flexSwitchCheckDefault" onclick="darkLightMode(this)" />

JavaScript

<script type="text/javascript">
    function darkLightMode(element) {
      (element.checked) ? document.body.classList.add('dark-mode') : document.body.classList.remove('dark-mode');
    }
</script>