<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<script src="jquery.min.js" type="text/javascript"></script> 
<script type="text/javascript"> 

//倒计时 
var countdown=60; 
function settime(val) { 
if (countdown == 0) { 
val.removeAttribute("disabled"); 
val.value="获取验证码"; 
countdown = 60; 
return false; 
} else { 
val.setAttribute("disabled", true); 
val.value="重新发送(" + countdown + ")"; 
countdown--; 
} 
setTimeout(function() { 
settime(val); 
},1000); 
} 
</script> 
</head> 
<body> 
<input type="number" class="code" placeholder="请输入手机验证码" required maxlength="6"> 
<input type="button" class="obtain generate_code" value=" 获取验证码" onclick="settime(this);"> 
</body> 
</html>