js中的cookie操作

//保存cookiefunction setCookie(cname, cvalue, exdays) {    var d = new Date();    d.setTime(d.getTime() + (exdays*24*60*60*1000));    var expires = "expires="+d.toUTCString();    document.cookie = cname + "=" + cvalue + "; " + expires;}//设置cookiefunction getCookie(cname) {    var name = cname + "=";    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);        if (c.indexOf(name) != -1) return c.substring(name.length, c.length);    }    return "";}//清除cookie  function clearCookie(name) {      setCookie(name, "", -999999);  }//删除cookiefunction delCookie(name){    var exp = new Date();    exp.setTime(exp.getTime() - 1);    var cval=getCookie(name);    if(cval!=null){        document.cookie= name + "="+cval+";expires="+exp.toGMTString();    }   }