返回頂部按鈕響應(yīng)滾動(dòng)且動(dòng)態(tài)顯示與隱藏

2024-05-06 16:09:38

字體：大中小

供稿：網(wǎng)友

返回頂部功能在很多的網(wǎng)站上都有，判斷滾動(dòng)參數(shù)動(dòng)態(tài)顯示與隱藏，下面的示例很實(shí)用，喜歡的朋友可以收藏下

很多的網(wǎng)站上都有返回頂部功能，判斷滾動(dòng)參數(shù)動(dòng)態(tài)顯示與隱藏，比較適合初學(xué)者

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<title>實(shí)現(xiàn)動(dòng)態(tài)的顯示回到頂部與否</title>

<style>

/*返回頂部*/

.back_top {width:45px;height:45px;background:url(back_top_new.png) 0 0;position:fixed;left:50%;margin-left:500px;bottom:105px;display:none;}

.back_top:hover{background:url(images/back_top_new.png) 0 -46px;}

</style>

</head>

<body>

<a title="返回頂部" href="javascript:void(0)" class="back_top"></a>

<script src="js/jquery-1.11.0.min.js"></script>

<script>

var mousewheelevt=(/Firefox/i.test(navigator.userAgent))? "DOMMouseScroll" : "mousewheel"; //FF doesn't recognize mousewheel as of FF3.x

if (document.attachEvent) //if IE (and Opera depending on user setting)

document.attachEvent("on"+mousewheelevt, function(e){

var t=document.body.scrollTop+document.documentElement.scrollTop;

if(t==0){

$(".back_top").css("display","none");

}

else{

$(".back_top").css("display","block");

}

});

else if (document.addEventListener) //WC3 browsers

document.addEventListener(mousewheelevt, function(e){

var t=document.body.scrollTop+document.documentElement.scrollTop;

if(t==0){

$(".back_top").css("display","none");

}

else{

$(".back_top").css("display","block");

}

}, false);

</script>

</body>

</html>