javascript与cookies的交互

        在搞Web2.0,使用惯了Ajax与服务器进行交互，没考虑过javascript如何在客户端保存数据。最近在做原型的时候发现如果javascript要在客户端保存数据还是很麻烦的事情。例如在页面左边的一个二级菜单，我如何在刷新页面的时候还保持我所选择的状态。
        javascript与cookies的交互：
<SCRIPT language=javascript>
function set_cookie (name, value) {
        var argv = set_cookie.arguments;
        var argc = set_cookie.arguments.length;
        var expires = new Date();
        var path = (argc > 3) ? argv[3] : null;
        var domain = (argc > 4) ? argv[4] : null;

        expires.setYear(4002);
        expires.setMonth(10);
        expires.setDate(1);
        expires.setHours(2);
        expires.setMinutes(3);

        st = name+"="+escape (value)+"; expires=" + expires.toGMTString()+ ((path == null) ? "" : ("; path=" + path)) + ((domain == null) ? "" : ("; domain=" + domain)) ;
         document.cookie =st;
}

function get_cookie(name) {
        var arg = name + "=";
        var alen = arg.length;
        var clen = document.cookie.length;
        var i = 0;
        while (i < clen) {
                var j = i + alen;
                if (document.cookie.substring(i, j) == arg) {
                        offset=j;
                        var endstr = document.cookie.indexOf (";", offset);
                        if (endstr == -1)
                                endstr = document.cookie.length;
                        return unescape (document.cookie.substring(offset, endstr));
                }
                i = document.cookie.indexOf(" ", i) + 1;
                if (i == 0)
                        break;
        }
        return null;
}

function del_cookie(name) {
        var expdate = new Date ();
        expdate.setTime (expdate.getTime()-1);
        set_cookie (name, "", expdate)
}

</SCRIPT>