| 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495 | <!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <meta name="viewport" content="width=device-width, initial-scale=1.0">    <title>Document</title>    <style>        body{            margin: 0;        }        .small-img{            width: 400px;            height: 400px;            position: relative;        }        .small-img img{            width: 100%;            height: 100%;            position: absolute;            top:0;            left: 0;        }        .box{            width: 200px;            height: 200px;            background-color: #fff;            position: absolute;            top:0;            left: 0;            opacity: 0.5;        }        .big-img,.small-img{            float: left;            margin-right: 20px;        }        .big-img{            width: 400px;            height: 400px;            overflow: hidden;            position: relative;        }        .big-img img{            width: 800px;            height: 800px;            position: absolute;            top:0;            left: 0;        }    </style></head><body>   <div class="container">    <div class="small-img">        <img src="./image/niu.png" alt="img">        <div class="box"></div>    </div>    <div class="big-img">        <img class="img-two" src="./image/niu.png" alt="img">    </div>   </div>    <script>    var smallImg = document.getElementsByClassName("small-img")[0];    var oBox = document.getElementsByClassName("box")[0];    var bigImg = document.getElementsByClassName("img-two")[0];    smallImg.onmousemove = function(e){        var _top = e.clientY-100;        var _left = e.clientX-100;        // 控制左侧边界        if(_left <= 0){            _left = 0        }        // 控制顶部边界        if(_top<=0){            _top = 0;        }        // 控制右侧边界        if(_left>=200){            _left = 200;        }        // 控制底部        if(_top>=200){            _top = 200;        }        oBox.style.top = _top + "px";        oBox.style.left = _left + "px";        bigImg.style.top = -2 * _top + "px";        bigImg.style.left = -2 * _left + "px";    }   </script></body></html>
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