简单实现js放大镜效果

时间：2021-05-18

本文实例为大家分享了js放大镜效果展示的具体代码，供大家参考，具体内容如下

具体代码如下:

<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Document</title> <style> body,div,img{ margin:0; padding:0; } img{ display:block; border:none; } #box{ position:absolute; top:20px; left:20px; width:350px; height:350px; box-shadow:3px 3px 10px 0 #111111; } #box img{ width:100%; height:100%; } #mark{ display:none; position:absolute; top:0; left:0; width:175px; height:175px; background:#000; opacity: 0.5; filter:alpha(opacity=50); cursor:move; } #boxRight{ display:none; position:absolute; top:20px; left:380px; width:350px; height:350px; overflow:hidden; } #boxRight img{ position:absolute; top:0; left:0; width:200%; height:200%; } </style></head><body> <div id='box'> <img src="img/iphone.jpg" alt=""> <div id='mark'></div> </div> <div id='boxRight'> <img src="img/iphone_big.jpg" alt=""> </div> <script> //放大镜的原理: 我们的mark横向是box的一半，纵向也是box的一半，那么右侧的大图横向（纵向）应该是左侧小图的2倍 var box = document.getElementById('box'); var mark = document.getElementById('mark'); var boxRight = document.getElementById('boxRight'); //设置mark这个盒子 function setPosition(e){ var top = e.clientY - box.offsetTop - (mark.offsetHeight/2); var left = e.clientX - box.offsetLeft - (mark.offsetWidth/2); //边界判断 var tempL = 0,tempT = 0; var minL = 0,minT = 0,maxL = box.offsetWidth - mark.offsetWidth,maxT = box.offsetHeight - mark.offsetHeight ; if(left<minL){ mark.style.left = minL + "px"; tempL = minL; }else if(left>maxL){ mark.style.left = maxL + "px"; tempL = maxL; }else{ mark.style.left = left + "px"; tempL = left; } if(top<minT){ mark.style.top = minT + "px"; tempT = minT; }else if(top>maxT){ mark.style.top = maxT + "px"; tempT = maxT; }else{ mark.style.top = top + "px"; tempT = top; } //右侧图片跟着运动:左侧移动多少，右侧跟着移动他的2倍即可 var oImg = boxRight.getElementsByTagName("img")[0]; oImg.style.left = -tempL*2 + "px"; oImg.style.top = -tempT*2 + "px"; } box.onmouseenter = function(e){ e = e || window.event; mark.style.display = "block"; setPosition(e); boxRight.style.display = "block"; } box.onmousemove = function(e){ e = e || window.event; setPosition(e); } box.onmouseleave = function(e){ e = e || window.event; mark.style.display = "none"; boxRight.style.display = "none"; } </script></body></html>

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