<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>图片延迟加载</title>
<style>
img{display:block;width:350px;height:245px;background:url(images/loading.png) center center no-repeat}
</style>
</head>
<body>
<div id="div">
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
<img src="" alt="" data-url="images/1.png" class="test"><br>
</div>
<script type="text/javascript">
var obj=document.getElementById("div").getElementsByTagName("img"),
h=window.innerHeight || document.documentElement.clientHeight;
for(var i=0;i<obj.length;i++){
obj[i].url=obj[i].getAttribute("data-url");
obj[i].top=obj[i].offsetTop;
obj[i].flag=true; //防止浏览器一直加载图片,这样图片加载成功后,滚动浏览器的时候就不会再加载图片了;
}
var fnLoad = function(obj){
var t = document.body.scrollTop || document.documentElement.scrollTop;
if(t+h>obj.top+200&&obj.top>t){ //给个200为了提高让用户看到图片加载状态,更加友好
setTimeout(function(){
obj.src=obj.url;
obj.flag=false;
},100)
}
}
window.onscroll = window.onload=function(){
for(var i=0;i<obj.length;i++){
if(obj[i].flag){
fnLoad(obj[i]);
}
}
}
</script>
</body>
</html>