封装cookie

function cookie(name,value,expires){

    switch(typeof value){
        case 'string':    //设置
            var exp='';
            if(expires){
                var oDate=new Date();
                oDate.setDate(oDate.getDate()+expires);
                exp=';expires='+oDate.toUTCString();
            }
            document.cookie=name+'='+encodeURIComponent(value)+exp;
            break;
        case 'undefined':    //获取
            if(document.cookie){
                var arr=document.cookie.split('; '),
                    aLen=arr.length,
                    nLen=name.length;
                for(var i=0; i<aLen; i++){
                    if(arr[i].substring(0,nLen)==name){
                        return decodeURIComponent(arr[i].substring(nLen+1));
                    }
                }
            }
            break;
        default:    //删除
            arguments.callee(name,'1',-1);
    }

}

使用方法：

cookie('username','wei\n魏...',14);    //设置cookie，14天后cookie删除
cookie('username','wei');    //设置cookie,浏览器关闭时cookie删除
cookie('age','21');    //设置cookie,注意用引号把数字变成字符串
cookie('username');    //获取cookie
cookie('username',null);    //删除cookie