<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
* {
margin: 0;
padding: 0;
}
.left {
width: 350px;
height: 350px;
border: 1px solid gray;
background: url(img/xiao.jpg);
position: relative;
}
.move {
width: 150px;
height: 150px;
background: orange;
opacity: 0.5;
position: absolute;
top: 0;
left: 0;
}
.right {
width: 400px;
height: 400px;
background: url(img/da.jpg);
position: absolute;
left: 400px;
top: 0;
border: 1px solid gray;
}
.move,
.right {
/* 默认隐藏 */
display: none;
}
</style>
</head>
<body>
<div class="left">
<div class="move"></div>
</div>
<div class="right"></div>
<script>
var left = document.querySelector('.left');
var right = document.querySelector('.right');
var move = document.querySelector('.move');
// 计算比例(大图未走过的距离 / 小图未走过的距离)
var rate = 400 / 200;
// 鼠标进入left, move和right显示出来
left.onmouseenter = function () {
move.style.display = 'block';
right.style.display = 'block';
left.onmousemove = function (e) {
e = e || window.event;
// 鼠标的位置保持在move的中心
var moveLeft = e.clientX - move.offsetWidth / 2;
var moveTop = e.clientY - move.offsetHeight / 2;
// 限制范围
if (moveLeft <= 0) moveLeft = 0
if (moveTop <= 0) moveTop = 0
if (moveLeft >= left.clientWidth - move.offsetWidth) moveLeft = left.clientWidth - move.offsetWidth;
if (moveTop >= left.clientHeight - move.offsetHeight) moveTop = left.clientHeight - move.offsetHeight;
move.style.left = moveLeft + 'px';
move.style.top = moveTop + 'px';
// right背景图片位置跟随move的移动修改
right.style.backgroundPosition = -moveLeft * rate + 'px ' + (-moveTop * rate) + 'px';
}
}
// 鼠标离开left, move和right隐藏
left.onmouseleave = function () {
move.style.display = 'none';
right.style.display = 'none';
}
</script>
</body>
</html>
