改个背景就这么难？？？

Question

想改动id="panelnine"里面的背景 ，用如下语句怎么不行啊？
         var a = "panelnine";
a.style.background="url(img/good.gif) no-repeat";

Answer 1

var a = document.getElementById("panelnine");

Answer 2

mymouse[0] = "document.getElementById('panelone')";
mymouse[0].style.background="url(img/good.gif) no-repeat"; 是不是有问题   没运行

Answer 3

mymouse[0] = "document.getElementById('panelone')";
=>
mymouse[0] = document.getElementById('panelone');
你引起来做什么 ？

Answer 4

var a = "panelnine";
这个太抽象了  用getElementByID

Answer 5

function GameStart()
{
     var mymouse = new Array(9);
                     mymouse[0] = document.getElementById('panelone');
                     mymouse[1] = document.getElementById('paneltwo');
                     mymouse[2] = document.getElementById('panelthree');
mymouse[3] = document.getElementById('panelfour');
mymouse[4] = document.getElementById('panelfive');
mymouse[5] = document.getElementById('panelsix');
mymouse[6] = document.getElementById('panelseven');
mymouse[7] = document.getElementById('paneleight');
mymouse[8] = document.getElementById('panelnine');

while(1)
  {
         random = parseInt(Math.random()*9,10);
 mymouse[random].style.background="url(img/good.gif) no-repeat";
  }
想让while里面的语句执行？