js实现淘宝浏览商品放大镜功能

时间:2020-10-28 h03580 人气:0

1、准备两张图片，其中一张图片分辨率为另一张图片的二倍。

2、前端页面布局

//box1位左侧原图，box2为右侧放大图额显示框,son为iv class="box1">
 <div class="son"></div>
 <div class="ceng"></div>
</div>
<div class="box2"></div>

3、js写逻辑

let box1=document.querySelector(".box1");
 let box2=document.querySelector(".box2");
 let son=document.querySelector(".son");
 let ceng=document.querySelector(".ceng");
 //鼠标移入：son，box2出现
 ceng.onmouseenter=function(){
  son.style.display="block"
  box2.style.display="block"
 }
 //鼠标移出：son，box2消失
 ceng.onmouseleave=function(){
  son.style.display="none"
  box2.style.display="none"
 }
 //鼠标移动：son的位置随鼠标移动，box2背景图的位置变化
 ceng.onmousemove=function(e){
  let sw=e.clientX-son.offsetWidth/2
  let sh=e.clientY-son.offsetHeight/2  
  if(sw>ceng.offsetWidth-son.offsetWidth){
   sw=ceng.offsetWidth-son.offsetWidth
  }
  else if(sw<=0){
   sw=0;
  }
  if(sh>ceng.offsetHeight-son.offsetHeight){
   sh=ceng.offsetHeight-son.offHeight
  }
  else if(sh<=0){
   sh=0;
  }
  son.style.left=sw+"px"
  son.style.top=sh+"px"
  box2.style.backgroundPosition=`${-2*sw}px ${-2*sh}px`
 }

完整代码

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>放大镜</title>
</head>
<style>
 *{
  margin: 0;
  padding: 0;
 }
 .box1{
  width: 500px;
  height:333px;
  /* border:1px solid red; */
  background: url('shatan.jpg') no-repeat;
  position: relative;
  float: left;
  box-sizing: border-box
 }
 .son{
  width: 100px;
  height: 100px;
  background-color: #fff;
  position: fixed;
  left:0;
  top:0;
  opacity: 0.7;
  display: none;
 }
 .ceng{
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  z-index: 100;
 }
 .box2{
  width: 200px;
  height:200px;
  border:1px solid red;
  background: url('shatan1.jpg') no-repeat;
  float: left;
  display: none;
 }
</style>
<body>
 <div class="box1">
  <div class="son"></div>
  <div class="ceng"></div>
 </div>
 <div class="box2"></div>
</body>
</html>
<script>
 let box1=document.querySelector(".box1");
 let box2=document.querySelector(".box2");
 let son=document.querySelector(".son");
 let ceng=document.querySelector(".ceng");
 ceng.onmouseenter=function(){
  son.style.display="block"
  box2.style.display="block"
 }
 ceng.onmouseleave=function(){
  son.style.display="none"
  box2.style.display="none"
 }
 ceng.onmousemove=function(e){
  let sw=e.clientX-son.offsetWidth/2
  let sh=e.clientY-son.offsetHeight/2  
  if(sw>ceng.offsetWidth-son.offsetWidth){
   sw=ceng.offsetWidth-son.offsetWidth
  }
  else if(sw<=0){
   sw=0;
  }
  if(sh>ceng.offsetHeight-son.offsetHeight){
   sh=ceng.offsetHeight-son.offHeight
  }
  else if(sh<=0){
   sh=0;
  }
  son.style.left=sw+"px"
  son.style.top=sh+"px"
  box2.style.backgroundPosition=`${-2*sw}px ${-2*sh}px`
 }
</script>

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