Pass variable to callback - nodejs

Question

I'm creating a simple Messenger bot, using unofficial Facebook Chat API (https://github.com/Schmavery/facebook-chat-api) and Node.js.

For now, I'm working on sending messages to specific users, on a specific time. Here's part of my code:

if(msgdate.getTime() <= currdate.getTime()){

    console.log(alarms[i].message);
    // output: test

    api.getUserID(alarms[i].user, (err, users) => {
        if(err) return console.error(err);

        api.sendMessage(alarms[i].message, users[0].userID);
        // TypeError: Cannot read property 'message' of undefined
    });
}

And, my question is: how could I pass alarms array to this callback, so I'd be able to send message to a specific user?

Try to use async/await. See if that helps.

palaѕн
– palaѕн

2017-10-03 14:43:47 +00:00
Commented Oct 3, 2017 at 14:43 — palaѕн
– palaѕн, Commented Oct 3, 2017 at 14:43

alexmac · Accepted Answer · 2017-10-03 14:43:51Z

1

Looks like that you change i variable somewhere, and because of that when callback is called alarms[i] is undefined. You need to store alarms[i] in a new variable and use it in callback:

let alarm = alarms[i];
api.getUserID(alarm.user, (err, users) => {
  if(err) {
    return console.error(err);
  }
  api.sendMessage(alarm.message, users[0].userID);
});

answered Oct 3, 2017 at 14:43

alexmac

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Comments

Madalozzo · Accepted Answer · 2017-10-03 14:55:27Z

Appear that you are using for loop outside. Try pass your var that way:

var alarm = alarm[i];
(function (alarm) {
    if(msgdate.getTime() <= currdate.getTime()){

    console.log(alarm.message);
    // output: test

    api.getUserID(alarm.user, (err, users) => {
        if(err) return console.error(err);

        api.sendMessage(alarm.message, users[0].userID);
        // TypeError: Cannot read property 'message' of undefined
    });
})(alarm);

Maybe you need to pass other vars too. Just put a comma and other var, example:

(function (alarm, user){
    // your code here
})(alarm, user);

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