javascript 动态得到当前控件、父控件、子控件，改变控件样式

得到当前元素并改变背景色：
         <script type="text/javascript"> 
             function changeColor(src){
              var obj=document.getElementsByTagName("td");
              for (i=0;i<obj.length;i++ ) 
             { 
               obj[i].style.backgroundColor="white"; 
             }

            src.style.backgroundColor="red";
             src.children.tags('a')[0].style.backgroundColor="cyan";
             alert(src.parentElement.tagName);
             }
            </script>

        <table>
            <tr>
                <td onclick="javascript:changeColor(this)"><a>aaa</a></td>
                <td onclick="javascirpt:changeColor(this)"><a>bbb</a></td>
                <td onclick="javascirpt:changeColor(this)"><a>ccc</a></td>
            </tr>
        </table>
    

注：改变背景图片
        obj[i].style.background="url(http://localhost:8080/images/abcimg.gif)";