用到定时器的js

var start =1;

var end =60;

function mobileRandTime()

{

if(start<end){

$("#mobileRandBtn").attr("disabled",true); 

start=start+1;

$("#mobileRandBtn").val(60-start+"秒后可重新发送");

setTimeout("mobileRandTime()",1000);

}else{

$("#mobileRandBtn").val("获取免费验证码");

$("#mobileRandBtn").attr("disabled",false); 

start=1;

}

}