Method for JS control button to be available after 10 seconds_javascript skills

<script language="javascript">
function start()
{
  document.getElementById("Button1").disabled = true;
  document.getElementById("Button1").value = 10;
  window.setTimeout("tick()",1000);
}
function tick()
{
  var time = new Number(document.getElementById("Button1").value);
  if(time>0)
  {
    document.getElementById("Button1").value = time-1;
    window.setTimeout("tick()",1000);
  }
  else
  {
    document.getElementById("Button1").disabled = false;
    document.getElementById("Button1").value = "保存";
  }
}
</script>
<form>
<INPUT TYPE="button" NAME="Button1" id="Button1">
</form>
<script language=javascript>
 start();
</script>