Select random visible row from table and clone it (with JS/jQuery)

I'm trying to get one random row from an array which is composed of 100 rows. Some are hidden, other are visible.

My aim is to get a random visible row, and clone it in another table. (visible and hidden row are classified, that's why I need that !)

My code :

            <table id="Random">
            </table>

            <table id="Classified">
                <tr id="Row1" style="display:none">
                    <td>1</td>
                    <td>2</td>
                    <td>3</td>
                    <td>4</td>
                </tr>

                <tr id="Row2">
                    <td>5</td>
                    <td>6</td>
                    <td>7</td>
                    <td>8</td>
                </tr>

                <tr id="Row3" style="display:none">
                    <td>9</td>
                    <td>10</td>
                    <td>11</td>
                    <td>12</td>
                </tr>

                <tr id="Row4">
                    <td>13</td>
                    <td>21</td>
                    <td>32</td>
                    <td>43</td>
                </tr>

                <tr id="Row5">
                    <td>15</td>
                    <td>26</td>
                    <td>37</td>
                    <td>48</td>
                </tr>
            </table>





            <script>
            $("#Random").html("");
            var randomtd = Math.floor(Math.random() * $('#Classified tr:visible').length)+1;
            var identifiedRow = $('#Classified tr').eq(randomtd)[0];

            $("#Random").html(identifiedRow);
            </script>