How @IrishEnergyBot used web scraping to help create awareness around Green Energy 🌱

import * as _ from "underscore";
import puppeteer = require("puppeteer");

const TIMEOUT_MS = 10000;

// or "roi" or "ni".
const REGION = "all";

(async () => {
  const browser = await puppeteer.connect({
    browserWSEndpoint: `wss://chrome.browserless.io?token=${process.env.BROWSERLESS_TOKEN}`,
  });

  try {
    const scrapedData = await scrape(await browser.newPage());
    console.log(JSON.stringify(scrapedData, undefined, 2));
  } finally {
    await browser.close();
  }
})();

async function scrape(page: puppeteer.Page) {
  // data frequently fails to load: empirically, if it hasn't loaded in the
  // first ~10s then we may as well fail.
  async function impatientGoto(url: string) {
    await page.goto(url, {
      waitUntil: "networkidle2",
      timeout: TIMEOUT_MS,
    });
  }
  async function impatientWaitForSelector(selector: string) {
    await page.waitForSelector(selector, {
      timeout: TIMEOUT_MS,
    });
  }

  // figures are contained in various divs, all with the class .stat-box. there
  // isn't a good way to find the ones we want without inspecting their text
  // content. this function extracts the number from the "stat box" under the
  // specified parent containing the specified phrase.
  async function extractStatBoxFigure(parent: string, keyPhrase: string) {
    const selector = `${parent} .stat-box`;
    await impatientWaitForSelector(selector);
    const statBoxesTextContents = await page.$$eval(selector, (elements) => {
      return elements.map((element) => {
        return element.textContent || "";
      });
    });

    const matchingStatBox = _.find(
      statBoxesTextContents,
      (s) => s.toLowerCase().indexOf(keyPhrase) >= 0
    );
    if (!matchingStatBox) {
      throw new Error(`no stat box found containing "${keyPhrase}"`);
    }
    return extractFirstNumber(matchingStatBox);
  }
​
  impatientGoto(`https://www.smartgriddashboard.com/#${REGION}/demand`);
  const demand_mw = await extractStatBoxFigure("#demand", "system demand");
​
  impatientGoto(`https://www.smartgriddashboard.com/#${REGION}/generation`);
  const gen_mw = await extractStatBoxFigure("#generation", "system generation");
​
  impatientGoto(`https://www.smartgriddashboard.com/#${REGION}/wind`);
  const wind_mw = await extractStatBoxFigure("#wind", "wind generation");

  return { gen_mw, demand_mw, wind_mw };
}

// extracts the first integer from a (potentially messy) blob of text, e.g.:
//   "     LATEST SYSTEM GENERATION      4,994 MW   " -> 4994
function extractFirstNumber(s: string) {
  // remove commas, e.g. 4,800 -> 4800
  const withoutCommas = s.replace(/,/g, "");

  // https://stackoverflow.com/questions/8441915/tokenizing-strings-using-regular-expression-in-javascript
  const tokens = withoutCommas.match(/[^\s]+/g) || [];

  const firstNumber = _.find(
    tokens.map((t) => parseInt(t, 10)),
    (i) => !isNaN(i)
  );
  if (!firstNumber) {
    throw new Error("no number found");
  }
  return firstNumber;
}