lovecoding
/
web0715


			
				
					
						
						
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							<!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;
        }
    </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"></div>
   </div> 
   <script>
    var smallImg = document.getElementsByClassName("small-img")[0];
    var oBox = document.getElementsByClassName("box")[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";
    }
   </script>
</body>
</html>