js放大镜代码 | 放大镜

js原生放大镜
<!DOCTYPE html>

<html>

<head>

    <title>放大镜</title>

    <meta charset="utf-8">

    <style type="text/css">

        *{

            margin: 0px;

            padding: 0px;

        }

        body{

            width: 960px;

            margin:40px auto;

        }

        #small{

            width: 300px;

            height: 200px;

            border:1px solid #eee;

            border-radius: 4px;

            position: relative;

        }

        #small img{

            width: %;

            height: %;

        }

        div    {

            float: left;

            margin-right: 10px;

        }

        #big{

            width: 300px;

            height: 200px;

            overflow: hidden;

            position: relative;

            border:1px solid #eee;

            border-radius: 4px;

            display: none;

        }

        #look_girl{

            position: absolute;

            left: 0px;

            top:0px;

        }

        #move{

            width: 100px;

            height: 100px;

            background:#;

            opacity: .;

            position: absolute;

            display: none;

            left: 0px;

            top: 0px;

        }

    </style>

</head>

<body>

    <div id="small">

        <img src="1.png">

        <p id="move"></p>

    </div>

    <div id="big">

        <img src="1.png" id="look_girl">

    </div>

</body>

<script type="text/javascript">

    var move = document.getElementById('move');

    var small = document.getElementById('small');

    var big = document.getElementById('big');

    var look_girl = document.getElementById('look_girl');

    small.onmousemove = function(event){

        event = event || window.event;

        this.style.cursor = 'move';

        // 计算move移动块的left值

        var move_left = event.clientX - this.offsetLeft - move.offsetWidth/;

        // 计算move移动块的top值

        var move_top = event.clientY - this.offsetTop - move.offsetHeight/;

        // 超出左边界赋值为0

        move_left = move_left <  ?  : move_left;

        // 超出右边界赋值为盒子宽度-移动块的宽度

        move_left = move_left > this.offsetWidth - move.offsetWidth ? this.offsetWidth - move.offsetWidth : move_left;

        // 超出上边界赋值为0

        move_top = move_top <  ?  : move_top;

        // 超出下边界赋值为盒子高度-移动块高度

        move_top = move_top > this.offsetHeight - move.offsetHeight ? this.offsetHeight - move.offsetHeight : move_top;

        // 修改移动块left、top值

        move.style.left = move_left + 'px';

        move.style.top = move_top + 'px';

        /*

            计算图片需要移动的坐标

            距离左边left    图片宽度      盒子宽度          距离左边left    图片宽度           盒子宽度

            big_x/(look_girl.offsetWidth-big.offsetWidth) = move_left/(small.offsetWidth-move.offsetWidth);

            big_y/(look_girl.offsetHeight-big.offsetHeight) = move_top/(small.offsetHeight-move.offsetHeight);

        */

        var big_x = move_left/(small.offsetWidth-move.offsetWidth) * (look_girl.offsetWidth-big.offsetWidth);

        var big_y = move_top/(small.offsetHeight-move.offsetHeight) * (look_girl.offsetHeight-big.offsetHeight);

        // 修改图片定位

        look_girl.style.left = -big_x + 'px';

        look_girl.style.top = -big_y + 'px';

    }

    small.onmouseover = function(){

        move.style.display = 'block';

        big.style.display = 'block';

    }

    small.onmouseout = function(){

        move.style.display = 'none';

        big.style.display = 'none';

    }

</script>

</html>
方法二更好