我这个代码复制上去了 之后，字符串方式添dom节点，看不到
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style type="text/css">
*{
margin: 0;
padding:0;
}
.loading{
width: 100%;
height: 100%;
background: #fff;
position: fixed;
z-index: 1000;
}
.loading>img{
position: absolute;
left: 0;
top: 0;
right: 0;
bottom: 0;
margin: auto;
}
div#containers>img{
width: 100%;
}
</style>
<script src="js/jquery-3.2.1.js" type="text/javascript" charset="utf-8"></script>
<script type="text/javascript">
$(function(){
var str='<div class="loading"><img src="icon/831.gif"/></div>';
$("body").append(str);
setInterval(function(){
$(".loading").fadeIn();
})
})
</script>
</head>
<body>
<img src="img/112.png"/>
<img src="img/QQ截图20171115113928.png"/>
<img src="img/继承的实例代码.png"/>
<img src="img/继承的实例代码对照图.png"/>
<img src="img/QQ截图20171119193152.png"/>
</body>
</html>
