JavaScript cookie基础操作

javascript操作cookie用document.cookie;

     首先是cookie名，对应的值value和有效期

     cookie的操作基本上是对字符串的操作和cookie有效期的设置

     如下操作

      window.onload = function() {
            setCookie("loginName", "sunjp", 2);
            var cookie = document.cookie;
            alert(cookie);
            delCookie("loginName1")
            alert(getCookie("loginName"));
            setCookie("loginName1", "sunjpcookie", 2);
            delCookie("loginName1")
            alert(getCookie("loginName"));
        }

     //添加cookie
        function setCookie(c_name, value, expiredays) {
            var exdate = new Date();
            exdate.setDate(exdate.getDate() + expiredays);
            document.cookie = c_name + "=" + escape(value) + ((expiredays == null) ? "" : ";expires=" + exdate.toGMTString());
        }
        //获得cookie 从cookie中截取对应名称的值
        function getCookie(c_name) {
            if (document.cookie.length > 0) {
                c_start = document.cookie.indexOf(c_name + "=")
                if (c_start != -1) {
                    c_start = c_start + c_name.length + 1
                    c_end = document.cookie.indexOf(";", c_start)
                    if (c_end == -1) c_end = document.cookie.length
                    return unescape(document.cookie.substring(c_start, c_end))
                }
            }
            return ""
        }
        //删除cookie  把对应的cookie的有效期设置成无效
        function delCookie(c_name) {
            var exdate = new Date();
            exdate.setDate(exdate.getDate() - 1);
            var value = getCookie(c_name);
            if (value != null) {
                document.cookie = c_name + "=" + value + ";expires=" + exdate.toGMTString();
            }
        }