介面處:

Session::set('login_id',$res['u_id']);//此處$res['u_id']為查詢的使用者表裡自增id
    $session_id = session_id();
    $result = array(
    'code' => 1,
    'message' => '登入成功',
    'session_id' => $session_id

    );

//js裡返回裡面

if(data.code == 1){

localStorage.setItem('s_id',data.session_id);

                    setCookie('s_id',data.session_id,3600);

}

//js中取

var s_id = localStorage.getItem("s_id");

//退出登入時

                localStorage.removeItem("s_id");