jQuery实现数秒后自动提交form的方法

<script language='javascript'>
<!--
$(document).ready(function(){
  // #formDownload ajaxForm
  $('#formDownload').ajaxForm({
    target:'#formDownloadWindows',suess:function(){
    }
  });
});
function jump(count,formId) {
  window.setTimeout(function(){
  count--;
  if(count > 0) {
    $('#jumpNum').html(count);
    jump(count,str);
  } else {
    $(str).submit();
  }
  }, 1000);
}  
//-->
</script>

<form action="/action/download" method="post" id="formDownload">
Wait <span id="jumpNum"></span> seconds
<input type="button" onclick="jump(30,"#formDownload");" />
</form>