如何用JS实现一个类似淘宝的放大镜功能-群英

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仿淘宝放大镜封装效果，供大家参考，具体内容如下

放大镜是做好了，但是没有下面小型导航无法选择放大图片，后期我会在封装出来的。由于考试当前考完试我会在推出vue的放大效果。以下是代码：

1.html代码

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>Title</title>
 <link href="css/index.css" rel="stylesheet">

</head>
<body>
<div class="magnify">
 <div class="magnify_conatiner">
 <div class="magnify_preview">
  <img class="sizeimg" src="../../../image/1.jpg" alt="">
  <div class="magnif_mask"></div>
  <div class="margnif_big">
  <img class="bigImg" src="../../../image/1.jpg" alt="">
  </div>
 </div>

 </div>
</div>
</div>
<script src="js/index.js"></script>
<script>

 var list = {
 BackgroundColor:'red',//遮罩层 颜色 必填
 Opacity:0.2,//遮罩层透明度 随意
 size:1.5 //放大倍数 必填

 }
 init(list)
 
</script>

</body>
</html>

2.css代码

.magnify_conatiner {
 width: 500px;
 height: 500px;
 margin: 50px 50px;
}

.magnify_conatiner .magnify_preview {
 position: relative;
 height: 400px;
 border: 1px silver solid;
 background-color: red;

}
div.magnify_preview .sizeimg {
 height: 100%;
 width: 100%;
}
.magnify_conatiner .magnify_preview .magnif_mask{
 position: absolute;
 top: 0;
 left: 0;
 opacity: .5;
 border: 1px solid #ccc;
 cursor: move;
 display: none;
}
.margnif_big{
 position: absolute;
 display: none;
 top: 0px;
 left: 501px;
 width: 450px;
 height: 450px;
 z-index: 999;
 border: 1px solid #ccc;
 overflow: hidden;
}
.margnif_big img{
 position: absolute;
 top: 0;
 left: 0;
}

3.封装的 js代码

function init(obj) {

 if (obj.BackgroundColor && obj.size) {
 var maskBigColor = obj.BackgroundColor
 var maskSize = obj.size
 var maskOpacity = obj.Opacity
 if(maskOpacity === undefined){
  maskOpacity = 0.2
 }
 var magnify_preview = document.querySelector('.magnify_preview')
 var mask = document.querySelector('.magnif_mask')
 var big = document.querySelector('.margnif_big')
 var bigIMG = document.querySelector('.bigImg')
 mask.style.height = obj.size * 100 + 'px'
 mask.style.width = obj.size * 100 + 'px'
 mask.style.backgroundColor = obj.BackgroundColor
 mask.style.opacity = maskOpacity
 magnify_preview.addEventListener('mouseover', function () {
  mask.style.display = 'block'
  big.style.display = 'block'

 })
 magnify_preview.addEventListener('mouseout', function () {
  mask.style.display = 'none'
  big.style.display = 'none'

 })
 magnify_preview.addEventListener('mousemove', function (e) {
  var x = e.pageX - this.offsetLeft
  var y = e.pageY - this.offsetTop
  var maskX = x - mask.offsetWidth / 2
  var maskY = y - mask.offsetHeight / 2
  var magnify_previewX = magnify_preview.offsetWidth
  var magnify_previewY = magnify_preview.offsetHeight
  var maskMaxX = magnify_preview.offsetWidth - mask.offsetWidth
  var maskMaxY = magnify_preview.offsetHeight - mask.offsetHeight
  if (maskX <= 0) {
  maskX = 0
  } else if (maskX >= magnify_previewX - mask.offsetWidth) {
  maskX = magnify_previewX - mask.offsetWidth
  }
  if (maskY <= 0) {
  maskY = 0
  } else if (maskY >= magnify_previewY - mask.offsetHeight) {
  maskY = magnify_previewY - mask.offsetHeight
  }
  mask.style.left = maskX + 'px'
  mask.style.top = maskY + 'px'

//大图片的移动距离 = 遮挡层的移动距离*大图片最大移动距离 / 遮挡层最大移动距离


  var bigMaxX = bigIMG.offsetWidth - big.offsetWidth
  var bigImgY = bigIMG.offsetHeight - big.offsetHeight
  var bigX = maskX * bigMaxX / maskMaxX
  var bigY = maskY * bigImgY / maskMaxY

  bigIMG.style.left = - bigX + 'px'
  bigIMG.style.top = - bigY + 'px'

 })


 } else {
 console.log('error')
 }

}

后期考完试我会继续的，图片大家自己更改吧，我没有用网图

效果展示