获取短信验证码倒计时

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>公益诉讼随手拍云平台注册</title>
<meta http-equiv="Content-Type" content="text/html; charset=gbk" />
<script src="http://libs.baidu.com/jquery/1.9.1/jquery.min.js"></script>

<script type="text/javascript">
        $(function() {
             
            var wait = 30; 
            function timeOut() { 
                if(wait != 0) {  
                    setTimeout(function() {  
                        $(\'#securityCode\').css("display","none");  
                        $(\'#showSecurityCode\').css("display","block");  
                        $(\'#showSecurityCode\').val(--wait+"秒后重新获取");  
                        timeOut();  
                    }, 1000);  
                }else{
                    $(\'#securityCode\').css("display","block");  
                    $(\'#showSecurityCode\').css("display","none");  
                    wait = 30;  
                }  
            }  
            
            
            $(\'#securityCode\').click(function(){
                
                timeOut();        
            
            });
        })
        
        
    </script>

</head>
<body>            

    <input type="button" id="securityCode" value="获取短信验证码">        
    <input type="button" id="showSecurityCode" style="display:none;" >        
                                                        
</body>
</html>