jquery 实现点击按钮后,倒计时60秒才能再次点击发送验证邮件

<input type="button" id="btn" value="免费获取验证码" />
<script type="text/javascript">
var wait=60;
function time(o) {
		if (wait == 0) {
			o.removeAttribute("disabled");			
			o.value="免费获取验证码";
			wait = 60;
		} else {
			o.setAttribute("disabled", true);
			o.value="重新发送(" + wait + ")";
			wait--;
			setTimeout(function() {
				time(o)
			},
			1000)
		}
	}
document.getElementById("btn").onclick=function(){time(this);}
</script>