js firstChild 、nextSibling、lastChild、previousSibling、parentNode

nextSibling下一个兄弟节点

previousSibling上一个兄弟

parentNode父亲节点

         <select><option value="zs">中山</option><option value="gz">广州</option><option value="zh">深圳</option><option value="zh">珠海</option></select>
         <script type="text/javascript">
               //取得<select>元素节点下的子元素的个数
               //var selectElement = document.getElementsByTagName("select")[0];
               //var size = selectElement.childNodes.length;
               //alert("select下共有"+size+"个元素");

               //取得“中山”字符串
               //var selectElement = document.getElementsByTagName("select")[0];
               //var zsElement = selectElement.firstChild;
               //var zs = zsElement.innerHTML;
               //alert(zs);

               //取得"广州"字符串
               //var selectElement = document.getElementsByTagName("select")[0];
               //var zsElement = selectElement.firstChild;
               //var gzElement = zsElement.nextSibling;
               //var gz = gzElement.innerHTML;
               //alert(gz);

               //取得"珠海"字符串
               //var selectElement = document.getElementsByTagName("select")[0];
               //var zhElement = selectElement.lastChild;
               //var zh = zhElement.innerHTML;
               //alert(zh);

               //取得"深圳"字符串
               //var selectElement = document.getElementsByTagName("select")[0];
               //var zhElement = selectElement.lastChild;
               //var szElement = zhElement.previousSibling;
               //var sz = szElement.innerHTML;
               //alert(sz);

               //删除"广州"元素
               var gzElement = document.getElementsByTagName("option")[1];
               var selectElement = gzElement.parentNode;
               selectElement.removeChild(gzElement);

         </script>