jqury点击返回顶部代码

效果请看右下角：代码如下：

<div class="totop">
<img src="https://www.cnblogs.com/images/cnblogs_com/aiwuxia/1249780/o_replay_tophover.jpg" alt="">
</div>
<script>

var topMain=$(".head").height()
$(window).scroll(function(){

if ($(window).scrollTop()>topMain){
$(".totop").slideDown(500);
}
else{
$(".totop").slideUp(500);
}
});
$(".totop").click(function(){$("body,html").animate({scrollTop:0},500)});
</script>