Qfyilyi

I have made a class which builds some data from api:

const http = require("http");



class VideoService {



    constructor() {

        this.items = ;

    }



    fetchVideos(token = "") {



        const url = `https://www.example.com`;



        http.getJSON(url).then((results) => {

            results.items.forEach((item, index) => {

                const vid = item.snippet.resourceId.videoId;



                this.items.push({

                    title: item.title,

                    date: item.publishedAt

                });



                console.log(this.items.length); // here length inreases, works here

            });



            if (typeof results.nextPageToken !== "undefined") {

                return this.fetchVideos(results.nextPageToken);

            }



        });

    }



    getVideos() {

        this.fetchVideos();



        console.log(this.items.length); // this returns 0 instead of all items fetched



        return this.items;

    }



}



module.exports = VideoService;

In another file, I am using it like this:

const videoService = require("../shared/videoService");



const videos = (new videoService()).getVideos();

console.log(videos);

The last console.log call always returns empty array instead of all data collected in items property of the above class.

Can anybody tell what I am missing here?

This happens because in your function fetchVideos(), you are making an http call which will be processed asynchronously. You can try to process it this way.

fetchVideos(token = "") {



    const url = `https://www.example.com`;



    return http.getJSON(url).then((results) => {

        results.items.forEach((item, index) => {

            const vid = item.snippet.resourceId.videoId;



            this.items.push({

                title: item.title,

                date: item.publishedAt

            });



            console.log(this.items.length); // here length inreases, works here

        });



        if (typeof results.nextPageToken !== "undefined") {

            return this.fetchVideos(results.nextPageToken);

        }

        else return new Promise((resolve, reject)=>{

          resolve();

        });



    });

}



getVideos() {

    return this.fetchVideos().then(function(){

       console.log(this.items.length); // this returns 0 instead of all items fetched

    return this.items;

    });

}

I suggest reading about promises and asynchronicity in javascript. Check this link:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise