jquery——three

css中样式：
<div class="wrap1">
<div class="wrap2">
<div class="wrap3">
<img src="object.gif" alt="The object casting a shadow" />
</div>
</div>
</div>
在jquery中可以改成：
$(document).ready(function(){
$("img.dropshadow")
.wrap("<div class='wrap1'><div class='wrap2'>" +
"<div class='wrap3'></div></div></div>");
});
<img src="ball.jpg" class = "dropshadow" alt="The object casting a shadow" />