Sharing variables across event callbacks in NodeJS

Question

I'm trying to build a FB messenger bot using messenger-bot module. Here's my sample code

bot.on('message', (payload, reply) => {
  let userData = payload.message.text;

  bot.getProfile(payload.sender.id, (err, profile) => {
    if (err) {
        console.log(err);
        // throw err
    }
    else {
        text = {
            "attachment":{
                "type":"template",
                "payload":{
                    "template_type":"button",
                    "text":"Pick an option?",
                    "buttons":[
                        {
                            "type":"postback",
                            "title":"Option 1",
                            "payload":"first_option"
                        },
                        {
                            "type":"postback",
                            "title":"Option 2",
                            "payload":"second_option"
                        }
                    ]
                }
            }
        };
        postBack(text, payload.sender.id, profile);
    }
  });
});

bot.on('postback', (payload, reply) => {
    let text = payload.postback.payload;
    bot.getProfile(payload.sender.id, (err, profile) => {
        //Do something with the userData and the selected option
    });
})

Now how do I access userData in the event callback for "postback" ? I could think of only the following solution

Pass the userData as part of the payload of the options, something like

"buttons":[
    {
        "type":"postback",
        "title":"Option 1",
        "payload":"first_option||"+userData
    }

and parse it again in the "postback" callback.

Is there a better way to do this? In other words how to share variables across callbacks in NodeJS/ JavaScript?

Answer 1

假设这需要服务多个用户，因此无法将userData的范围扩大，那么您要么将其持久化在数据库/缓存中，然后从“回发”中进行查询，要么使用将其作为有效内容的一部分的想法。