js图片懒加载（可视区域加载）
来源：互联网 发布：mac数据恢复软件 编辑：程序博客网 时间：2024/04/28 22:48
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>图片懒加载(可视区域加载)</title>
<style>
* {padding: 0px;margin: 0px;}
html,body {width: 100%;min-height: 100%;}
#SB {margin: 0;padding: 0;list-style: none;}
#SB .in {border: 1px solid red;margin: 10px;text-align: center;height: 400px;width: 400px;float: left;}
.in img {border: none;vertical-align: middle;height: 400px;width: 400px;}
</style>
</head>
<body>
<ul id="SB">
<li class="in"><img src="" data-imgurl="img/1.jpg"></li>
<li class="in"><img src="" data-imgurl="img/2.jpg"></li>
<li class="in"><img src="" data-imgurl="img/3.jpg"></li>
<li class="in"><img src="" data-imgurl="img/4.jpg"></li>
<li class="in"><img src="" data-imgurl="img/5.jpg"></li>
<li class="in"><img src="" data-imgurl="img/6.jpg"></li>
<li class="in"><img src="" data-imgurl="img/7.jpg"></li>
<li class="in"><img src="" data-imgurl="img/8.jpg"></li>
<li class="in"><img src="" data-imgurl="img/9.jpg"></li>
<li class="in"><img src="" data-imgurl="img/10.jpg"></li>
<li class="in"><img src="" data-imgurl="img/11.jpg"></li>
<li class="in"><img src="" data-imgurl="img/12.jpg"></li>
<li class="in"><img src="" data-imgurl="img/13.jpg"></li>
<li class="in"><img src="" data-imgurl="img/14.jpg"></li>
<li class="in"><img src="" data-imgurl="img/15.jpg"></li>
<li class="in"><img src="" data-imgurl="img/16.jpg"></li>
<li class="in"><img src="" data-imgurl="img/1.jpg"></li>
<li class="in"><img src="" data-imgurl="img/2.jpg"></li>
<li class="in"><img src="" data-imgurl="img/3.jpg"></li>
<li class="in"><img src="" data-imgurl="img/4.jpg"></li>
<li class="in"><img src="" data-imgurl="img/5.jpg"></li>
<li class="in"><img src="" data-imgurl="img/6.jpg"></li>
<li class="in"><img src="" data-imgurl="img/7.jpg"></li>
<li class="in"><img src="" data-imgurl="img/8.jpg"></li>
<li class="in"><img src="" data-imgurl="img/9.jpg"></li>
<li class="in"><img src="" data-imgurl="img/10.jpg"></li>
<li class="in"><img src="" data-imgurl="img/11.jpg"></li>
<li class="in"><img src="" data-imgurl="img/12.jpg"></li>
<li class="in"><img src="" data-imgurl="img/13.jpg"></li>
<li class="in"><img src="" data-imgurl="img/14.jpg"></li>
<li class="in"><img src="" data-imgurl="img/15.jpg"></li>
<li class="in"><img src="" data-imgurl="img/16.jpg"></li>
<li class="in"><img src="" data-imgurl="img/1.jpg"></li>
<li class="in"><img src="" data-imgurl="img/2.jpg"></li>
<li class="in"><img src="" data-imgurl="img/3.jpg"></li>
<li class="in"><img src="" data-imgurl="img/4.jpg"></li>
<li class="in"><img src="" data-imgurl="img/5.jpg"></li>
<li class="in"><img src="" data-imgurl="img/6.jpg"></li>
<li class="in"><img src="" data-imgurl="img/7.jpg"></li>
<li class="in"><img src="" data-imgurl="img/8.jpg"></li>
<li class="in"><img src="" data-imgurl="img/9.jpg"></li>
<li class="in"><img src="" data-imgurl="img/10.jpg"></li>
<li class="in"><img src="" data-imgurl="img/11.jpg"></li>
<li class="in"><img src="" data-imgurl="img/12.jpg"></li>
<li class="in"><img src="" data-imgurl="img/13.jpg"></li>
<li class="in"><img src="" data-imgurl="img/14.jpg"></li>
<li class="in"><img src="" data-imgurl="img/15.jpg"></li>
<li class="in"><img src="" data-imgurl="img/16.jpg"></li>
</ul>
<script type="text/javascript">
var aImages = document.getElementById("SB").getElementsByTagName('img'); //获取id为SB的文档内所有的图片
loadImg(aImages);
window.onscroll = function() { //滚动条滚动触发
loadImg(aImages);
};
//getBoundingClientRect 是图片懒加载的核心
function loadImg(arr) {
for(var i = 0, len = arr.length; i < len; i++) {
if(arr[i].getBoundingClientRect().top < document.documentElement.clientHeight && !arr[i].isLoad) {
arr[i].isLoad = true; //图片显示标志位
//arr[i].style.cssText = "opacity: 0;";
(function(i) {
setTimeout(function() {
if(arr[i].dataset) { //兼容不支持data的浏览器
aftLoadImg(arr[i], arr[i].dataset.imgurl);
} else {
aftLoadImg(arr[i], arr[i].getAttribute("data-imgurl"));
}
arr[i].style.cssText = "transition: 1s; opacity: 1;" //相当于fadein
}, 500)
})(i);
}
}
}
function aftLoadImg(obj, url) {
var oImg = new Image();
oImg.onload = function() {
obj.src = oImg.src; //下载完成后将该图片赋给目标obj目标对象
}
oImg.src = url; //oImg对象先下载该图像
}
</script>
</body>
</html> 0 0
