Store data from twitter api javascript (nodejs)

Question

I seem to be having an issue. I'm trying to export data from the twitter api but I can't. Here's what my code looks like :

/// Twitter.js
module.exports = Twitter

function Twitter(twitter) {
    this.twitter = twitter
}

Twitter.prototype.friends = function(params) {
    this.twitter.get('friends/list', params, (err, data) => {
        if (err)
            console.log(err)

        console.log(data) // this prints data to the console but 
                          // I want to export and save in a data structure
                          // array or object
    }
}

///bot.js
var Twit = require('twit')
var config = require('/path_to_config.js')
var init = Twit(config)
var Twitter = require('/path_to_Twitter.js')

var bot = new Twitter(config)
bot.friends({ screen_name: 'myscreenname'})

If I try returning the data parameter it returns undefined and if I push data.users to an array it returns an empty array . Any help is and will be appreciated.

Answer 1

Looks like it might be an async problem. I'm not familiar with the Twitter API, but you could try (or a variation of) the following:

Twitter.prototype.friends = function(params, cb) {
  this.twitter.get('friends/list', params, cb);
};

And then:

var bot = new Twitter(config)
bot.friends({ screen_name: 'myscreenname'}, (err, data) => {
  // Do something with the data here.
  console.log('data', data);
});

It's the same logic, but moving the async response to a place more useful to what you might be trying to do.

Answer 2

I suggest using Promises to allow the calling code to work with the returned data:

Twitter.prototype.friends = function(params) {
    return new Promise((resolve, reject) => {
        this.twitter.get('friends/list', params, (err, data) => {
           if (err) {
               reject(err);
           } else {
               resolve(data);
           }
        });
     });
}

...
var bot = new Twitter(config)
bot.friends({ screen_name: 'myscreenname'}).then((data) => {
    // do something with data
    console.log(data);
}).catch((err) => {
    console.error(err);
});

Answer 3

The third parameter you are passing into the get function is a callback . If you add value to an array inside the callback and try to access it before the callback is invoked, that array will be empty/undefined.

The way I see it, you have two options:

1. Look into doing the work you need inside your callback. Either directly, or by passing a callback into the function. Edit: Check out @JohnnyCoder's answer above for the latter.
2. Consider using a Promise . If the Twitter API doesn't support it, you can consider turning the callback into a promise (by wrapping around the result). For a fairly simple tutorial on how to convert a callback into a Promise using the native JavaScript API, check out this blog post.