如何让一个层关闭之后，就算刷新页面了也不显示。除非关闭页面再次打开

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 
<html> 
    <head> 
        <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> 
        <title>一个层关闭之后，就算刷新页面了也不显示。除非关闭页面再次打开</title> 
        <style type="text/css"> 
            #myDiv{ 
                border:1px solid red; 
                background:#cccccc; 
                width:100px; 
                height:100px; 
            } 
            #mySpan{ 
                cursor:pointer; 
            } 
        </style> 
        <script language="JavaScript" type="text/javascript"> 
        function closeDiv(){ 
            document.getElementById("myDiv").style.display = "none"; 
            document.cookie = "isClose"; 
        } 
        window.onload = function(){ 
            var arrStr = document.cookie; 
            if(arrStr.indexOf("isClose") > -1){ 
                closeDiv(); 
            } 
        } 
        </ script> 
    </head> 
    <body> 
         
        <div id="myDiv"><span onclick="closeDiv()" id="mySpan">关闭</span></div> 
    </body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]

如何让一个层关闭之后，就算刷新页面了也不显示。除非关闭页面再次打开_javascript技巧