<script type="text/javascript">$(".btn").click(function(){	$(this).countdown(60);});$.fn.extend({	 countdown:function(seconds){	 	var time=seconds;		var timer;		var _this=$(this);		_this.addClass("on");		_this.find("a").html("重新获取("+seconds+"s)");		timer=setInterval(function(){			time--;			if(time<0){				clearInterval(timer);				_this.removeClass("on");				_this.find("a").html("获取验证码");				time=seconds;			}else{				_this.find("a").html("重新获取("+time+"s)");			}		},1000);		 }});</script>