js操作cookie的方法

<script type="text/javascript">
    //创建Cookie
    function createCookie(name,value,hour) {
        if (hour) {
            var date = new Date();
            date.setTime(date.getTime()+(hour*60*60*1000));
            var expires = "; expires="+date.toGMTString();
        }
        else var expires = "";
        document.cookie = name+"="+value+expires+"; path=/";
    }
    //读取Cookie    
    function readCookie(name) {
        var nameEQ = name + "=";
        var ca = document.cookie.split(';');
        for(var i=0;i < ca.length;i++) {
            var c = ca[i];
            while (c.charAt(0)==' ') c = c.substring(1,c.length);
            if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
        }
        return null;
    }
    //清空Cookie
    function eraseCookie(name) {
        createCookie(name,"",-1);
    }

    //设置cookiename值为 cookievalue过期时间1小时
    createCookie('cookiename','cookievalue',1);

</script>

参考资料
http://www.quirksmode.org/js/cookies.html
http://stackoverflow.com/questions/14573223/set-cookie-and-get-cookie-with-javascript