js 3秒後自動跳轉頁面

<script>
var secs = 3; //倒計時的秒數 
var URL ;
function Load(url){
URL = url;
for(var i=secs;i>=0;i--) 
{ 
  window.setTimeout('doUpdate(' + i + ')', (secs-i) * 1000); 
} 
}

function doUpdate(num) { 
if(num == 0) { window.location = URL; }
}


$('#sub').click(function(){
var name = $('input[name=name]').val();
var num = $('select[name=num]').val();
var sex = $('input[name=sex]').val();
var kc = $('select[name=kc]').val();
var tel = $('input[name=tel]').val();
var dq = $('select[name=dq]').val();
var add = $('input[name=add]').val();
var hk = $('input[name=hk]').val();
var email = $('input[name=email]').val();
var descr = $('#tt_note').val();
var post_id = <?php echo $_REQUEST['post_id']; ?>;
var url="dozx.php";
var postdata = "name="+name+"&num="+num+"&sex="+sex+"&kc="+kc+"&tel="+tel+"&dq="+dq+"&add="+add+"&hk="+hk+"&email="+email+"&descr="+descr+"&post_id="+post_id;
//alert(postdata);exit();
$.post(url,postdata,function(data){
//alert(data);exit();
if(data.c == 1){
alert(data.m);
var ur = "alipayapi.php?WIDout_trade_no="+data.o.ordercode+"&WIDsubject="+data.o.subj+"&WIDtotal_fee="+data.o.total_fee;
Load(ur);
return false;
}else if(data.c == 0){
alert(data.m);
return false;
}

})
})


</script>