通过json的序列化和反序列化在cookie中存入数组，读取cookie数组，并给cookie数组加元素

                        var username = $( ".nick_name_true"). html();//取到要判断是cookie中是否存在的值，没有则添加

var agree_user = $. cookie( "agree_user");//取到需要的cookie

if( agree_user == undefined){如果不存在这个cookie则给他添加值

                                var argee_user_list = new Array();

                                 argee_user_list.push(username);

// agree_user = [{ username}];//设置json格式[{key:value}],这里注意用了ES6语法容易报错不采用

agree_user = JSON. stringify( agree_user_list) //转换成JSON字符串

$. cookie( "agree_user", agree_user,{ expires: 365});//存入cookie

} else{如果已经有cookie则添加元素

agree_user = JSON. parse( agree_user)//解析取出的的JSON字符串cookie

var hasName_list = [];

for( var i= 0; i< agree_user. length; i++){//循环解析过的cookie

var hasName = agree_user[ i]

if( username == hasName){//找到和验证项的相同项

hasName_list. push( username)

}

}

if( hasName_list. length == 0){如果没有相同项则添加

agree_user. push( username)

agree_user = JSON. stringify( agree_user)//把添加好的数组转化成json字符串

$. cookie( "agree_user", agree_user,{ expires: 365});

}

}