JS实现电商商品展示放大镜特效

时间:2021-04-02 人气:0
知识点
1.使用children获取字标签组
2.求当前鼠标坐标
3.碰撞检测
4.大小盒子通过比例同步
运行效果
代码
<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>Title</title>
 <style>
 * {
  margin: 0;
  padding: 0;
  list-style: none;
  border: none;
 }

 #box {
  width: 350px;
  height: 350px;
  margin: 100px 0 0 100px;
  position: relative;
 }

 #box > #small_box {
  height: 100%;
  width: 100%;
  border: 1px solid #cccccc;
  box-sizing: border-box;
  position: relative;
 }

 #box > #small_box > img {
  height: 100%;
  width: 100%;
 }

 #box > #small_box > #mask {
  width: 100px;
  height: 100px;
  background-color: rgba(255, 255, 0, .4);
  position: absolute;
  left: 0;
  top: 0;
  cursor: move;
  /*隐藏*/
  display: none;
 }

 #box > #big_box {
  height: 600px;
  width: 600px;
  border: 1px solid #cccccc;
  position: absolute;
  left: 360px;
  top: 0;
  overflow: hidden;
  display: none;
 }
 #box > #big_box > img{
  position: absolute;
  left: 0;
  top: 0;
 }
 #list {
  margin: 20px 0 0 100px;
 }

 #list ul li {
  float: left;
  margin: 5px;
  cursor: pointer;
 }
 </style>
</head>
<body>
<div id="box">
 <div id="small_box">
 <img src="images/pic001.jpg" alt="">
 <span id="mask"></span>
 </div>
 <div id="big_box">
 <img src="images/pic01.jpg" alt="">
 </div>
</div>
<div id="list">
 <ul>
 <li><img src="images/pic0001.jpg" alt=""></li>
 <li><img src="images/pic0002.jpg" alt=""></li>
 <li><img src="images/pic0003.jpg" alt=""></li>
 <li><img src="images/pic0004.jpg" alt=""></li>
 </ul>
</div>
<script src="../../MyTools/MyTools.js"></script>
<script>
 window.addEventListener('load', function (ev) {
 // 1. 获取标签
 var box = myTools.$('box'), s_box = box.children[0], b_box = box.children[1], mask = s_box.children[1];
 var list_Lis = myTools.$('list').getElementsByTagName('li');
  b_img = b_box.children[0];
 // 2. 监听鼠标进入小盒子
 s_box.addEventListener('mouseover', function (evt) {
  // 2.1 显示隐藏内容
  mask.style.display = 'block';
  b_box.style.display = 'block';
  // 2.2 监听鼠标移动
  s_box.addEventListener('mousemove', function (evt1) {
  var e = evt1 || window.event;
  // 2.3 求出鼠标坐标
  var pointX = e.pageX - box.offsetLeft - mask.offsetWidth * 0.5;
  var pointY = e.pageY - box.offsetTop - mask.offsetHeight * 0.5;
  // 2.4 边界碰撞检测
  if (pointX < 0) {
   pointX = 0
  } else if (pointX >= s_box.offsetWidth - mask.offsetWidth - 2) {
   pointX = s_box.offsetWidth - mask.offsetWidth - 2;
  }
  if (pointY < 0) {
   pointY = 0
  } else if (pointY >= s_box.offsetHeight - mask.offsetHeight - 2) {
   pointY = s_box.offsetHeight - mask.offsetHeight - 2;
  }
  // 2.5 让放大镜走起来
  mask.style.left = pointX + 'px';
  mask.style.top = pointY + 'px';
  // 2.6 让大盒子中图片走起来
  /*
  * smallX / bigX = sBox.width / bBox.width
  * bixX = smallX/(sBox.width / bBox.width)
  * */
  b_img.style.left = -pointX / (s_box.offsetWidth/b_box.offsetWidth) + 'px';
  b_img.style.top = -pointY / (s_box.offsetHeight/b_box.offsetHeight) + 'px';

  })
 });
 // 3. 监听鼠标离开小盒子
 s_box.addEventListener('mouseout', function (evt) {
  // 2.1 隐藏内容
  mask.style.display = 'none';
  b_box.style.display = 'none';
 });
 // 4. 监听鼠标点击li标签

 for (var i = 0; i < list_Lis.length; i++) {
  (function (i) {
  var li = list_Lis[i];
  li.addEventListener('mouseover',function (ev1) {
   s_box.children[0].src = 'images/pic0'+(i+1)+'.jpg';
   b_img.src = 'images/pic0'+(i+1)+'.jpg';
  });
  })(i);
 }
 });
</script>
</body>
</html>
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