<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no">
<title>2.3 单指拖拽--运动</title>
<style>
body {
height: 2000px;
}
.backtop {
position: fixed;
right: 20px;
bottom: 20px;
width: 45px;
height: 45px;
line-height: 45px;
text-align: center;
background-color: rgba(0, 0, 0, 0.6);
border-radius: 50%;
color: #fff;
font-size: 30px;
-webkit-tap-highlight-color: transparent;
/*transform: translate3d(x, y, 0);*/
}
</style>
</head>
<body>
<a href="#" id="backtop" class="backtop">↑</a>
<script>
var backtop = document.getElementById('backtop');
var curPoint = {
x: 0,
y: 0
};
backtop.addEventListener('click', function () {
// move(this, 0, 0);
move(this, -10 + curPoint.x, -10 + curPoint.y);
curPoint.x += -10;
curPoint.y += -10;
}, false);
function move(el, x, y) {
x = x || 0;
y = y || 0;
el.style.transform = 'translate3d(' + x + 'px, ' + y + 'px, 0)';
}
</script>
</body>
</html>