How to scrape web with the subpage in parallel?

I saw many web scraping tutorial but I can't find the pattern that would scrape the web with subpages.

Here is the sequence

1. Scrape the first page to find several URLs
2. Go to each URLs, find several URLs
3. Go to another layer of URLs, read the content from the table

I can find many URL that teaches how to do the step 1. But further down I can't find any good example. In addition I tried X-ray but it doesn't work well because my URL is part of the parent item.

Here is some sample code:

var request = require('request');
var cheerio = require('cheerio');

var url = 'https://news.ycombinator.com';

request(url, function (error, response, html) {
    if (!error && response.statusCode == 200) {
        var $ = cheerio.load(html);
        $('span.comhead').each(function(i, element){
            // Obtain the URL of the news
            var a = $(this).prev();
            var subUrl = a.attr('href');

            // Go to that news and obtain the title
            request(subUrl, function (error, response, html) {
                if (!error && response.statusCode == 200) {
                    var $ = cheerio.load(html);
                    var title = $("title").text();
                    console.log(title);
                }
            });
        });
    }
});

But the cheerios each should be running in sequential way. Are there any way that I can scrape the page in parallel?

Thanks for the help

You can do this easily with x-ray. See below code for example:

var Xray = require('x-ray');
var x = Xray();
var baseUrl = 'https://news.ycombinator.com'; // set base url
x(baseUrl, { // scrape base url
    title1: x('a', [{links1:'@href'}]) // store links in array
})(function(err, obj1) { // pass array to next fx
    obj1.forEach(function(links.link) {
        // assuming links.link stores '/sample-link-to-crawl-83792',
        x(baseUrl+links.link, { // append base url to link and crawl
            title2: x('a', [{links2:'@href'}])
        })(function(err, obj2){
            obj2.forEach(function(links2.link) { // for each link in obj2
                console.log(link) // should print link to console
            });
        });
    });
});

You can continue like this or simply create a function that returns a promise and pass the scanned url's to it at anytime. Then you watch for the completed promise and do what you want with the returned data.