下载网站打开页面后间隔多少时间才显示下载链接地址的代码

<a id="readylink" href="javascript:download();" class="submitbutton">请等待</a> 
<a id="downloadlink" href="https://3water.com/" class="submitbutton" style="display:none;">下载</a> <script type="text/javascript"> 
var timeout="25"; 
function countdown() 
{ 
if (timeout<=0) 
{ 
document.getElementById("readylink").style.display="none"; 
document.getElementById("downloadlink").style.display="block"; 
} 
if (timeout>0) 
{ 
document.getElementById("readylink").innerHTML='请稍等'+timeout+'秒'; 
setTimeout("countdown()",1000); 
} 
timeout--; 
} 
countdown(); 
function download() { 
if(timeout>0) { 
alert('请稍等，服务器正在取得相关资源。'); 
} 
} 
</script>