网购网站悬浮图片放大镜

效果图：

  CSS代码块：

<style>
    * {
        margin: 0;
        padding: 0;  
    }
    .box {
        width: 500px;
        height: 500px;
        margin: 10px;
        border: 1px solid #ccc;
        position: relative;
    }

    .big {
        width: 400px;
        height: 300px;
        position: absolute;
        top: 0;
        left: 510px;
        border: 1px solid #ccc;
        overflow: hidden;
        display: none;
    }

    .mask {
        width: 175px;
        height: 175px;
        background: rgba(255, 255, 225, 0.4);
        position: absolute;
        top: 0;
        left: 0;
        cursor: move;
        display: none;
    }

    .small {
        position: relative;
    }

    .box img {
        vertical-align: top;
    }

    #bigBox img {
        position: absolute;
    }
</style>

HTML代码块

<div class="box" id="box">
    <div id="smallBox" class="small ">
        <img src="img/Rog-1.jpg" width="500">
        <div id="mask" class="mask"></div>
    </div>
    <div id="bigBox" class="big">
        <img src="img/Rog-1.jpg" alt="" id="bigPic">
    </div>
</div>

Scrpit代码块

<script>
    var smallBox = document.getElementById('smallBox');
    var mask = document.getElementById('mask');
    var bigBox = document.getElementById('bigBox');
    var box = document.getElementById('box')
    var bigPic = document.getElementById('bigPic')
    //鼠标经过小盒子，显示大盒子
    smallBox.onmouseover = function() {
        bigBox.style.display = "block";
        mask.style.display = "block";

    }
    smallBox.onmouseout = function() {
        bigBox.style.display = "none";
        mask.style.display = "none";
    }
    smallBox.onmousemove = function(event) {
        //遮罩跟随鼠标
        var event = event || widow.event;
        var pageX = event.pageX || event.clientX + document.documentElement.scrollLeft;
        var pageY = event.pageY || event.clientY + document.documentElement.scrollTop;
        //计算mask的位置
        var targetX = pageX - box.offsetLeft - mask.offsetWidth / 2;
        var targetY = pageY - box.offsetLeft - mask.offsetHeight / 2;
        //限制mask移动范围
        if (targetX < 0) targetX = 0;
        if (targetY < 0) targetY = 0;
        if (targetX > smallBox.offsetWidth - mask.offsetWidth) targetX = smallBox.offsetWidth - mask.offsetWidth;
        if (targetY > smallBox.offsetHeight - mask.offsetHeight) targetY = smallBox.offsetHeight - mask.offsetHeight;
        mask.style.left = targetX + "px";
        mask.style.top = targetY + "px";
        //按照比例移动大图
        var bigToMove = bigPic.offsetWidth - bigBox.offsetWidth;
        var maskToMove = smallBox.offsetWidth - mask.offsetWidth;
        var rate = bigToMove / maskToMove;
        bigPic.style.left = -rate * targetX + "px";
        bigPic.style.top = -rate * targetY + "px";
    }
</script>