js通过图片切换实现开关按钮（一）

<style>
.box1{
width: 100px;
height: 50px;
border: 1px solid #ccc;
background: url(img/closed.png) no-repeat;
}
.changeBg{
width: 100px;
height: 50px;
border: 1px solid #ccc;
background: url(img/opened.png) no-repeat;
}
</style>

<script type="text/javascript">
function change(n){
var su = confirm("是否确定");
var emediv=document.getElementById('mydiv'+n);
if(su==true){
if(emediv.className=="box1"){
//此处写后台交互
emediv.className="changeBg";
}else{
emediv.className="box1";
}
}
}
</script>

<div class="box1" onclick="change(1)" id="mydiv" > </div>