Web Scraping with JS, Node and puppeteer

webscrape_with_puppeteer.js

const puppeteer = require('puppeteer');
const cheerio = require('cheerio');

function get_browser() {
    return puppeteer.launch();
}
function instantiate_page(browser) {
  return browser.newPage();
}
class PageLoadError extends Error {
  constructor(message, page, address) {
    super(message);
    this.page = page;    
    this.address = address;
  }
};
function navigate_page(address, page) {
  return page.goto(address, { waitUntil: 'networkidle2',
                              timeout: 240000})
    .then(() => Promise.resolve(page))
    .catch((err) => Promise.reject(new PageLoadError(err, page, address)));
}
function fetch_page_content(page) {
  return page.content()
    .then(() => Promise.resolve(page));
}
function restart(error) {
    if (error instanceof PageLoadError) {
      error.page.close();
      return load_page(error.address);
    } else {
      throw error;
    }
}
load_page = function(url) {
  return get_browser()
    .then(instantiate_page)
    .then(navigate_page.bind(null, url))
    .then(fetch_page_content)
    .catch(restart)
}

function select_html(page) {
    return page.$eval(BODY_LYRICS_SELECTOR, (el) => el.innerHTML)
}
function print_some_part_of_it(lyrics_html) {
  let $ = cheerio.load(lyrics_html, {decodeEntities: false});
  $('body').contents().each(function(i, elm) {
    if (elm.tagName === 'a') {
      console.log($(elm).text());
    }
  });
}

load_page('https://genius.com/The-mamas-and-the-papas-california-dreamin-lyrics')
.then(select_html)
.then(print_some_part_of_it)

const BODY_LYRICS_SELECTOR = "body > routable-page > ng-outlet > song-page > div > div > div.song_body.column_layout > div.column_layout-column_span.column_layout-column_span--primary > div > defer-compile:nth-child(2) > lyrics > div > section > p";