Galeria com javascript

<h2>Galeria</h2>
            <script type="text/javascript">

                for(var i=1;i<=38;i++){
                    document.write('<a href="imagens/galeria/foto'+i+'.jpg" class="html5lightbox" data-group="mygroup" ><img src="imagens/galeria/foto'+i+'m.jpg" class="thumb" ></a>');
                }
            </script>