用js实现简单放大镜效果，供大家参考，具体内容如下
此处放大镜实现的效果就是当鼠标放置在图片上会有半透明遮罩，图片的一个区域就会被放大，然后展示在右边。当鼠标移动时右边的大图片也会局部移动。这里的放大并不是真正的放大，而是等比例移动。下面是实现的代码：
css样式代码如下：
<style> .s_box{width:400px;height: 300px;position: absolute;left: 50px;top:100px;} .s_box img{width: 400px;height: 300px;} .s_box span{width: 130px;height: 100px;background: rgba(200,200,200,0.5);position: absolute;left:0;top:0;display: none;cursor:move;} .b_box{width: 400px;height: 300px;overflow: hidden;position: absolute;left:500px;top:100px;display: none;} .b_box img{width: 1200px;height: 900px;position: absolute;left:0;top:0;} .list{margin: 0;padding: 0;list-style: none;position: absolute;left:50px;top:430px;} .list li{float: left;margin: 0 10px;} .list li img{width: 100px;height: 80px;} </style>
html代码如下：
<body> <div> <img src="https://www.jb51.net/img/large1.jpg" alt=""> <span></span> </div> <div> <img src="https://www.jb51.net/img/large1.jpg" alt=""> </div> <ul> <li><img src="https://www.jb51.net/img/large1.jpg" alt=""></li> <li><img src="https://www.jb51.net/img/large2.jpg" alt=""></li> </ul> </body>
js主要代码如下：
// 分析: // 1.选择元素 // 2.绑定事件 // 3.进入的时候显示元素 // 4.移动：遮罩层跟随鼠标移动的同时计算遮罩层的移动比例 、右侧大图，等比例移动 // 5.离开的时候隐藏元素 <script> class Large{ constructor(){ this.sBox = document.querySelector(".s_box"); this.sImg = document.querySelector(".s_box img"); this.sSpan = document.querySelector(".s_box span"); this.bBox = document.querySelector(".b_box"); this.bImg = document.querySelector(".b_box img"); // 点击小图切换大图的按钮 this.li = document.querySelectorAll(".list li"); } addEvent(){ var that = this; this.sBox.onmouseover = function(){ that.over(); } this.sBox.onmousemove = function(eve){ var e = eve || window.event; that.move(e); } this.sBox.onmouseout = function(){ that.out(); } // 切换图片按钮的点击事件：根据布局做出调整 for(var i=0;i<this.li.length;i++){ this.li[i].onclick = function(){ that.sImg.src = this.children[0].src; that.bImg.src = this.children[0].src; } } } over(){ this.sSpan.style.display = "block"; this.bBox.style.display = "block"; } move(e){ // 计算遮罩层跟随鼠标移动时的left和top var l = e.pageX - this.sBox.offsetLeft - this.sSpan.offsetWidth/2; var t = e.pageY - this.sBox.offsetTop - this.sSpan.offsetHeight/2; // 边界限定 if(l<0) l=0; if(t<0) t=0; if(l > this.sBox.offsetWidth - this.sSpan.offsetWidth){ l = this.sBox.offsetWidth - this.sSpan.offsetWidth; } if(t > this.sBox.offsetHeight - this.sSpan.offsetHeight){ t = this.sBox.offsetHeight - this.sSpan.offsetHeight; } // 设置遮罩层的位置 this.sSpan.style.left = l + "px"; this.sSpan.style.top = t + "px"; // 根据遮罩层移动的距离计算比例 var x = l / (this.sBox.offsetWidth - this.sSpan.offsetWidth); var y = t / (this.sBox.offsetHeight - this.sSpan.offsetHeight); // 根据上一步得到的比例，计算右侧大图要移动的当前值 this.bImg.style.left = (this.bBox.offsetWidth - this.bImg.offsetWidth) * x + "px"; this.bImg.style.top = (this.bBox.offsetHeight - this.bImg.offsetHeight) * y + "px"; } out(){ this.sSpan.style.display = "none"; this.bBox.style.display = "none"; } } // 启动 var l = new Large(); l.addEvent(); </script>
实现效果：
