简单的代码，js在aspx中提示XXX未定义，帮忙看看。

Question

代码如下，提示myImage1未定义
<script language="JavaScript">
var d=0
function JM_fade(ob){
var myImage1=document.getElementById("myImage1");
if (d==0) {ob.filters.alpha.opacity+=1} else {ob.filters.alpha.opacity-=1}
if (ob.filters.alpha.opacity==100){d=1;} else if (ob.filters.alpha.opacity==0){d=0}
}
setInterval("JM_fade(myImage1)",10)
</script>
<img src="images/Golf1.gif" alt="" id="myImage1" style="filter:alpha(opacity=0)"/>

Answer 1

<script language="JavaScript">
var d=0
function JM_fade(ob){
var myImage1=document.getElementById("myImage1");
if (d==0) {ob.filters.alpha.opacity+=1} else {ob.filters.alpha.opacity-=1}
if (ob.filters.alpha.opacity==100){d=1;} else if (ob.filters.alpha.opacity==0){d=0}
}
setInterval("JM_fade(myImage1)",10)   //错误出在这里！！你的myImage1变量只是定义在 JM_fade函数里的局部变量
</script>

Answer 2

<script language="JavaScript">
var d=0
function JM_fade(ob){
var myImage1=document.getElementById("myImage1");
if (d==0) {ob.filters.alpha.opacity+=1} else {ob.filters.alpha.opacity-=1}
if (ob.filters.alpha.opacity==100){d=1;} else if (ob.filters.alpha.opacity==0){d=0}
}
setInterval("JM_fade(myImage1)",10); // setInterval(function(){JM_fade(document.getElementById("myImage1"))},10)这样试试
</script>