js点击获取—通过JS获取图片的绝对对坐标位置

一、通过JS获取鼠标点击时图片的相对坐标位置

源代码如下所示：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        .wrap{
            width:300px;
            height: 200px;
            background: #ccc;
            position: relative;
        }
        .ball{
            width:20px;
            height: 20px;
            background: red;
            border-radius: 50%;
            position: absolute;
        }
        .box {
            width: 400px;
            height: 400px;
            overflow: auto;
        }

    </style>
</head>
<body>
<div class="box">
    <div class="wrap">
        <img  src="images/test.jpg" alt="">
        <div class="container"></div>
    </div>
</div>

<script src="js/jquery-2.1.3.min.js"></script>
<script type="text/javascript">
    $(\'.wrap\').click(function(e){
        var radius=10;//半径
        var offset=$(this).offset();
        var top=e.pageY-offset.top-radius+"px";
        var left=e.pageX-offset.left-radius+"px";
        //$(\'.wrap\').append(\'<div class="ball" style="top:\'+top+\';left:\'+left+\'"></div>\');
        $(\'.container\').html(\'<div class="ball" style="top:\'+top+\';left:\'+left+\'"></div>\');
        alert(top+"_"+left);
    })
</script>
</body>
</html>