复制代码代码如下: 
<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);"><strong><span style="font-size:12px;color:#3333ff;">1.用js插入一张图片并控制图片宽高</span></strong></span>
复制代码代码如下:
<script type="text/javascript" src="jquery-1.4.2.min.js"></script> 
<script type="text/javascript"> 
$(function(){ 
$(".bd").append("<div id='mainbg'/>"); 
$("#mainbg").append("<img id='im' src='a82a2e72e7af59296db0d63e3d2ecc5e!n1200.jpg' />"); 
recover(); 
$(window).resize(function(e) { 
recover(); 
}); 
}); 
function recover(){ 
var winw = $(window).width(); 
var winh = $(window).height(); 
$("#im").attr({width:winw, height:winh}); 
} 
</script> 
利用CSS按比例缩放背景图片 
复制代码代码如下:
<style type="text/css"> 
.bd{ 
background-image:url(a82a2e72e7af59296db0d63e3d2ecc5e!n1200.jpg); 
background-repeat:no-repeat; 
background-size:cover; 
} 
</style>
<body class="bd"> 
</body>
