<script type="text/javascript">
var tid;
var bClicked = false;
function sbm(){
    if(bClicked){
        alert("提示您，請不要重複遞交");
        return false;   
    }
    bClicked = true;
    tid = setTimeout("doit()", 10000);
    //document.forms[0].submit();
}

function doit(){
    if(tid!=null){clearTimeout(tid);tid=null;}
    bClicked = false;
}
</script>

<form action="xxx" target="hf">
  <input name="btn" type="button" onclick="sbm();" value=" 提交 ">
</form>
<iframe name="hf"></iframe>