Getting 'undefined' when passing an array through Express res.render function

Question

My first attempt at a basic node app.

If I test run this file (> node index.js) with console.log(eventsArray) in it instead, the array successfully prints out data from the scraper module in the command window, so my scraper module is working.

And if I set eventsArray = ['this','is,'a','test','array']; in index.js as a test, then these strings do show up on homepage like I want after running the app with Express, so Express + Jade template are working (no need to include my ejs template here since it's working).

The problem: If I try to run the app as shown below (> node index.js), eventsArray appears to be 'undefined' when it's passed into the res.render function, so nothing shows up on localhost:3000 (homepage)

index.js:

var myScraperModule = require('./src/scraper');  // import my scraper function
var express = require('express');
var app = express();

eventsArray =  myScraperModule.getEvents(); // returns an array

app.set('port', process.env.PORT || 3000);

app.get('/', function(req, res) {
    res.render('index.ejs', {data : eventsArray }); // send array to homepage
});


app.listen(app.get('port'), function(){
    console.log("express started")
});

scraper.js:

// basic web scraper using scraperjs module
var scraperjs = require('scraperjs');

function getEvents(){
scraperjs.StaticScraper.create('https://examplewebsite.com/')
    .scrape(function($) {
        return $("p").map(function() { 
              return $(this).html();
            }
       }).get();
    })
    .then(function(data) { 
        //... clean up the data and return it as eventsClean
        return eventsClean;  // return an array of strings
      } 
    });
}

module.exports = getEvents;

Answer 1

Your getEvents returns nothing, besides of this scraperjs.StaticScraper.create is async function it returns a promise.

You should return async result from getEvents:

function getEvents(){
    return scraperjs.StaticScraper
      .create('https://examplewebsite.com/')
      .scrape(function($) {
        return $("p").map(function() { 
          return $(this).html();
        }).get();
       })
       .then(function(data) { 
         //... clean up the data and return it as eventsClean
         return eventsClean;  // return an array of strings
       });
}

And use it in the action with creating a promise chain:

app.get('/', function(req, res) {
  myScraperModule
    .getEvents()
    .then(eventsArray => res.render('index.ejs', {data : eventsArray }));
});