在jsp页面中显示26个英文字母

<span id="showLetter"></span>   
                    <script type="text/javascript">
                    var start =65, end = 90, str;
                    var size = 2;
                    var contextStr="";
                    for (str = start; str <= end; str++) {
                    var letter = String.fromCharCode(str);
                    contextStr+='<a href="ShowSingerServlet?opt=show&s_namefirst='+letter+'">'+letter+'</A>';
                    }
                    document.getElementById("showLetter").innerHTML=contextStr;
                </script>