JS实现的动态背景渐变

<div id="scrollBackground" style="height: 150px; background-image: url(../images/hfbg.jpg);
background-attachment: initial; background-origin: initial; background-clip: initial;
background-color: initial; background-position: 0px -1925px; background-repeat: no-repeat no-repeat;">
</div>

<script type="text/javascript">    // hf Background scroll
window.onload = function () {
var scrollBackground = {
object: document.getElementById("scrollBackground"),
endTop: 3657,
nowTop: 0
};
var scrollInterval = setInterval(function () {
scrollBackground.nowTop = (scrollBackground.nowTop != scrollBackground.endTop) ? (scrollBackground.nowTop + 1) : 0;
scrollBackground.object.style.backgroundPosition = "0px -" + scrollBackground.nowTop + "px";
}, 50);
}
</script>