求几张图片渐变显示代码

<script language=javaScript>
<!--//
sandra0 = new Image();
sandra0.src = "image1.gif";
sandra1 = new Image();
sandra1.src = "image2.gif";
sandra2 = new Image();
sandra2.src = "image3.gif";
var i_strngth=1
var i_image=0
var imageurl = new Array()
imageurl[0] ="图片名称1.gif"
imageurl[1] ="图片名称2.gif"
imageurl[2] ="图片名称3.gif"
function showimage() {
if(document.all) {
if (i_strngth <=110) {
testimage.innerHTML="<img style='filter:alpha(opacity="+i_strngth+")' src="+imageurl[i_image]+" border=0>";
i_strngth=i_strngth+10
var timer=setTimeout("showimage()",100)
}
else {
clearTimeout(timer)
var timer=setTimeout("hideimage()",1000)
}
}
if(document.layers) {
clearTimeout(timer)
document.testimage.document.write("<img