设立按钮在倒计时内不可用

发送短信后,按钮倒计时时间内,按钮不可用.

var timer;
		$(document).ready(function(){
			$("#veribtn").click(function(){
				$.ajax({
					type:"POST",
					url:"userAction!vefiCode.action",
					data:"null",
					success:function(){
						timer = setInterval(countDown, 1000);
					}
				});
			});
		});
		
		var maxtime = 60;
		function countDown() {
			if (maxtime >= 0) {
				$("#veribtn").attr("disabled", "disabled");
				$("#veribtn").val(maxtime + "秒后重新获取验证码");
				--maxtime;
			} else {
				clearInterval(timer);
				$("#veribtn").val("点击获取短信验证码");
				$("#veribtn").removeAttr("disabled");
				maxtime = 60;
			}
		}