判断一个页面正在读取中，还没有完全打开

<div id="loading"> <img src="/Images/indicator_medium.gif" /> </div>
<script type="text/javascript">
//    if(document.readyState=="interactive" || document.readyState=="complete"
//    || typeof(document.readyState) == "undefined") //firefox
//    {
        document.getElementById("loading").style.display = "none";
    //}
    </script>
        
    </form>