css樣式:
#btnTop{
position: fixed;
bottom: 2%;
right: 2%;
background: white;
width: 45px;
height: 50px;
text-align: center;
line-height: 50px;
font-size: 35px;
border: 1px solid darkgray;
display: none;
}
#btnTop:HOVER {
border: 1px solid lightskyblue;
background: gainsboro;
cursor: pointer;
color:white;
}
標籤:
<span id="btnTop" onclick="returnTop()" title="返回頂部">∧</span>
JS:
// 當網頁向下滑動 20px 出現"返回頂部" 按鈕
window.onscroll = function() {
scrollFunction()
};
function scrollFunction() {
if(document.body.scrollTop > 20) {
document.getElementById("btnTop").style.display = "block";
} else {
document.getElementById("btnTop").style.display = "none";
}
}
// 點擊按鈕,返回頂部
function returnTop() {
document.body.scrollTop = 0;
document.documentElement.scrollTop = 0;
}