getCaptchaDownloadURL.js

const puppeteer = require('puppeteer-core');
const fs = require('fs');

// first start browser with this command:
// chromium-browser --incognito --remote-debugging-port=9222 --no-first-run --no-default-browser-check --user-data-dir=/tmp/t
// then visit: https://www.google.com/recaptcha/api2/demo and navigate to audio captcha
// then this script will yield the audio url

let wsChromeEndpointurl = null;

(async () => {
  if (process.argv.length != 3) {
    if (fs.existsSync('browser.log')) {
      let logContents = fs.readFileSync('browser.log').toString();
      var regex = /DevTools listening on (.*)/gi;
      let match = regex.exec(logContents);
      if (match) {
        wsChromeEndpointurl = match[1];
      } else {
        process.exit('Could not get ws URL');
      }
    }
  } else {
    console.error('Usage: node getCaptchaDownloadURL.js ws://127.0.0.1:9222/devtools/browser/2f7d4355-4c7b-44a0-be0c-e9402493f586')
  }

  let browser = null;

  try {
    browser = await puppeteer.connect({
      browserWSEndpoint: wsChromeEndpointurl,
    });

    const page = (await browser.pages())[0];

    await page.waitForSelector(`iframe[title="recaptcha challenge"]`, {timeout: 5000});

    const elementHandle = await page.$('iframe[title="recaptcha challenge"]');
    const frame = await elementHandle.contentFrame();

    let captchaAudioURL = await frame.evaluate(function () {
      // check if we get bad bot text
      var bad = document.querySelector('.rc-doscaptcha-body-text');
      if (bad) {
        return bad.innerHTML;
      }
      
      var el = document.getElementById('audio-source');
      if (el) { 
        return el.getAttribute('src') 
      } else { 
        var other = document.querySelector('.rc-audiochallenge-tdownload-link');
        if (other) {
          return other.getAttribute('href') 
        }
      }
      return 'none';
    });

    console.log(captchaAudioURL);
    
  } catch (err) {
    console.error(err);
  } finally {
    if (browser) {
      await browser.disconnect();
    }
  }
})();