基于javascript实现放大镜特效

本文实例为大家分享了javascript实现放大镜特效的具体代码，供大家参考，具体内容如下

我们在逛pc端商城时，鼠标放到商品上经常会看到一个类似放大镜效果的蒙层，

<!DOCTYPE html><html><head><meta charset=\"UTF-8\"><title></title><style type=\"text/css\">* {margin: 0px;padding: 0px;}#min {width: 350px;height: 350px;border: 1px solid #ccc;position: absolute;left: 50px;top: 50px;}#min img {width: 350px;height: 350px;}#max {width: 500px;height: 500px;position: absolute;left: 500px;top: 50px;border: 1px solid #ccc;overflow: hidden;display: none;}#max img {position: absolute;left: 0;top: 0;}#mask {width: 200px;height: 200px;background: rgba(255, 0, 0, 0.5);position: absolute;left: 0px;top: 0px;cursor: pointer;display: none;}</style></head><body><div id=\"min\"><img src=\"img/min.jpg\" alt=\"\" /><div id=\"mask\"></div></div><div id=\"max\"><img src=\"img/max.jpg\" id=\"maxImg\" /></div><script type=\"text/javascript\">// 1.鼠标经过小盒子，遮罩层出现，大盒子出现// 2.遮罩层跟随鼠标移动// 3.遮罩层移动，大盒子里的图片反方向移动var oMin = document.getElementById(\'min\');var oMax = document.getElementById(\'max\');var oMask = document.getElementById(\'mask\');var oMaxImg = document.getElementById(\'maxImg\');oMin.onmousemove = function(e) {// 1.鼠标经过小盒子，遮罩层和大盒子出现oMask.style.display = \'block\';oMax.style.display = \'block\';// 2.拿到鼠标在小盒子上的坐标var minX = e.clientX - oMin.offsetLeft;var minY = e.clientY - oMin.offsetTop;// 3.将鼠标放置在遮罩层的中间minX = minX - oMask.offsetWidth / 2;minY = minY - oMask.offsetHeight / 2;// 4.遮罩层可以移动的最大距离var maxWidth = oMin.offsetWidth - oMask.offsetWidth;var maxHeight = oMin.offsetHeight - oMask.offsetHeight;// 限定遮罩层的位置if (minX > maxWidth) {minX = maxWidth;} else if (minX <= 0) {minX = 0;}if (minY > maxHeight) {minY = maxHeight;} else if (minY <= 0) {minY = 0;}// 设定遮罩层的偏移oMask.style.left = minX + \'px\';oMask.style.top = minY + \'px\';// 大图片移动的距离=遮罩层移动的距离/遮罩层可以移动的最大距离*大图片最大移动距离var ratioX = minX / maxWidth;var ratioY = minY / maxHeight;// 计算出大图片的移动距离oMaxImg.style.left = -ratioX * (oMaxImg.offsetWidth - oMax.offsetWidth) + \'px\';oMaxImg.style.top = -ratioY * (oMaxImg.offsetHeight - oMax.offsetHeight) + \'px\';};// 鼠标移开，遮罩层和大盒子消失oMin.onmouseout = function() {oMask.style.display = \'none\';oMax.style.display = \'none\';}</script></body></html>

效果图：