//点击发送按钮触发事件
function sendMsg(){
	var time = 60; //设定倒计时时间为60s
	var obj = $('#btn');//发送验证码按钮对象
	settime(obj,time);
}

function settime(obj,time){
	if(time==0){
		obj.attr('disabled',false);
		obj.val("点击发送验证码");
		time = 60;
		return;
	}else{
		obj.attr('disabled',true);
		obj.val(time+"s后重发");
		time--;
	}
	setTimeout(function(){
		settime(obj,time)
	},1000)
}