<script language="javascript">
var goto_top_type = -1;
var goto_top_itv = 0;
function goto_top_timer() {
var y = goto_top_type == 1 ? document.documentElement.scrollTop
: document.body.scrollTop;
var moveby = 15;
y -= Math.ceil(y * moveby / 100);
if (y < 0) {
y = 0;
}
if (goto_top_type == 1) {
document.documentElement.scrollTop = y;
} else {
document.body.scrollTop = y;
}
if (y == 0) {
clearInterval(goto_top_itv);
goto_top_itv = 0;
}
}
function goto_top() {
if (goto_top_itv == 0) {
if (document.documentElement && document.documentElement.scrollTop) {
goto_top_type = 1;
} else if (document.body && document.body.scrollTop) {
goto_top_type = 2;
} else {
goto_top_type = 0;
}
if (goto_top_type > 0) {
goto_top_itv = setInterval('goto_top_timer()', 50);
}
}
}
</script>
<a href="javascript:void(0)" onclick="goto_top()">【返回顶部】</a>