短信验证倒计时

<style type="text/css">

.btn { 
    border: 0;
    width:120px;
    height:40px;  
    line-height: 40px; 
    float:left;
    color: white;
    background-color: #08c;
    border-radius: 20px;
    text-align: center;
    text-decoration: none;
}
</style>
</head>
<body>
<input type="button" class="btn" id="code" value="获取验证码" onclick="codeButton()">
</body>
<script type="text/javascript">
function codeButton(){
    var code = $("#code");
    code.attr("disabled","disabled");
    setTimeout(function(){
     code.css("opacity","0.8");
    },1000)
    var time = 60;
    var set=setInterval(function(){
    code.val("("+--time+")秒后重新获取");
    }, 1000);
    setTimeout(function(){
    code.attr("disabled",false).val("重新获取验证码");
    clearInterval(set);
    }, 60000);
}
</script>