javascript Cookie的增、删、改 、查

//添加cookie：cookie名称，cookie值，以及在多少小时后过期。这里约定expireHours为0时不设定过期时间，即当浏览器关闭时cookie自动消失
function addcookie(name, value, expireHours) {
    var cookieString = name + "=" + escape(value);
    //判断是否设置过期时间
    if (expireHours > 0) {
        var date = new Date();
        date.setTime(date.getTime + expireHours * 3600 * 1000);
        cookieString = cookieString + "; expire=" + date.toGMTString();
    }
    document.cookie = cookieString;
}
//设置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());
}

//获取指定名称的cookie值:该函数返回名称为name的cookie值，如果不存在则返回空
function getcookie(name) {
    var strcookie = document.cookie;
    var arrcookie = strcookie.split("; ");
    for (var i = 0; i < arrcookie.length; i++) {
        var arr = arrcookie[i].split("=");
        if (arr[0] == name) return arr[1];
    }
    return "";
}

//删除cookie
function 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();
}