Wait for an API request to finish so it can pass a variable for the next async iteration to use it – Shopify

const request = require('request');
const fs = require('fs');
const json2csv = require('json2csv');
const async = require('async');
const _ = require('underscore');
const RateLimiter = require('limiter').RateLimiter;
const flatten = require('flat');
const limiter = new RateLimiter(1, 500);
const credentials = require('dotenv').config();

let apikey = "someapikey";
let password = "somepassword";
let storeName = "somestorename";

let baseurl = 'https://' + apikey + ':' + password + '@' + storeName + '.myshopify.com';
let numOrders = 0;
let ordersList = [];
let countordersList = 0;
var nextLink;
var apiurl;



let getOrders = function(page, callback) {
    console.log(page);
    if (page == 1) {
        apiurl = baseurl + '/admin/orders.json?status=any&limit=250';
    }
    console.log(apiurl);

    request({
        url: apiurl,
        json: true
    }, function(error, response, body) {

        if (!error && response.statusCode === 200) {

            if (response.headers.link && response.headers.link.indexOf(`rel="next"`) > -1) {
                console.log(apiurl);

                try {
                    // Try to parse our the string we need
                    nextLink = response.headers.link;

                    // If there's a previous link, remove the first part of the string entirely
                    if (nextLink.indexOf(`rel="previous"`) > -1) {
                        nextLink = nextLink.substr(nextLink.indexOf(",") + 2, nextLink.length);
                    }

                    // Parse the remaining string for the actual link
                    nextLink = nextLink.substr(1, nextLink.indexOf(">") - 1);
                    // READY - CALL THE NEXT SET WITH NEXTLINK
                    apiurl = nextLink;
                } catch (ex) {
                    console.log("ERROR");
                    console.log(response.headers);
                }
            } else {
                console.log("ALL ORDERS EXPORTED");
                console.log(response.headers);
            }




            let newList = [];
            for (i = 0; i < body.orders.length; i++) {
                newList.push(flatten(body.orders[i]));
            }

            ordersList = ordersList.concat(newList);
            countordersList += ordersList.length;
            console.log('Orders received: ' + countordersList + ' / ' + numOrders);
            console.log();

            json2csv({
                    data: ordersList,
                    fields: ['order_number', 'email', 'financial_status', 'processed_at', 'fulfillment_status:', 'currency', 'total_price', 'browser_ip', 'gateway', 'billing_address.first_name', 'billing_address.last_name', 'billing_address.address1', 'billing_address.address2', 'billing_address.company', 'billing_address.city', 'billing_address.zip', 'billing_address.province', 'billing_address.province_code', 'billing_address.country', 'billing_address.country_code', 'billing_address.phone', 'shipping_address.first_name', 'shipping_address.last_name', 'shipping_address.address1', 'shipping_address.address2', 'shipping_address.company', 'shipping_address.city', 'shipping_address.zip', 'shipping_address.province_code', 'shipping_address.country_code', 'shipping_address.phone', 'line_items.0.name', 'line_items.0.quantity', 'line_items.0.price', 'line_items.0.sku', 'line_items.1.name', 'line_items.1.quantity', 'line_items.1.price', 'line_items.1.sku', 'line_items.2.name', 'line_items.2.quantity', 'line_items.2.price', 'line_items.2.sku', 'line_items.3.name', 'line_items.3.quantity', 'line_items.3.price', 'line_items.3.sku', 'line_items.4.name', 'line_items.4.quantity', 'line_items.4.price', 'line_items.4.sku']
                },
                function(err, csv) {
                    if (err) console.log(err);
                    fs.appendFile(storeName + '.csv', csv, function(err) {
                        if (err) throw err;
                        ordersList = [];
                    });
                });

            callback();

        }


    })
}

request({
    url: baseurl + '/admin/orders/count.json?status=any',
    json: true
}, function(error, response, body) {
    if (!error && response.statusCode === 200) {
        numOrders = body.count;
    }
    console.log();
    if (numOrders > 700000) {
        numOrders = 700000;
    }
    console.log('Total: ' + body.count);
    console.log('Processing: ' + numOrders);
    console.log();
    let numPages = numOrders / 250;
    let r = _.range(1, numPages + 1);

    async.forEach(r, function(page, callback) {
        limiter.removeTokens(1, function() {
            getOrders(page, callback);
        })

    }, function(err) {
        // Called when all are finished
        console.log('Total: ' + ordersList.length);
        console.log();


    });


});