opties.php

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.9.1/themes/redmond/jquery-ui.css" />
<div class="wrap">
    <div id="icon-options-general" class="icon32">
    <br />
    </div>
<h2>Afwezigheid Instellen</h2>


<?php
    if($_POST['hidden-check']=='Y') {
    //Form data sent
    echo '<div class="updated"><p><strong>Instelling opgeslagen</strong></p></div>';
    //echo saved message
    }

    else {
        //Normal page display
    }
?>

<form name="afwezigzijn" action="afwezigheid-include.php" method="post">
    <input type="hidden" name="hidden-check" value="Y">
    <input type="radio" id="geenafwezig" name="groep" value="geen-afwezigheid" /> Geen Afwezigheid<br />
    <input type="radio" id="welaanwezig" name="groep" value="data-selecteren"> Data selecteren:<br />

    <div id="data">
        <p>Van: <input type="text" class="datepicker" name="datevan" /></p>
        <p>Tot: <input type="text" class="datepicker" name="datetot" /></p>
    </div>

    <p class="submit">
    <input type="submit" name="Submit" value="Submit" />
    </p>
</form>

    <script src="http://code.jquery.com/jquery-1.8.2.js"></script>
    <script src="http://code.jquery.com/ui/1.9.1/jquery-ui.js"></script>
    <script>

    $(function () {
        $('#data').hide();
    });

    $(function () {
        $('#geenafwezig').click(function () {
            $('#data').hide('fast');
         });

    $('#welaanwezig').click(function () {
            $('#data').show('fast');
        });
        });

    $(function() {
        $( ".datepicker" ).datepicker();
    });
    </script>