Puppeteer Shadow Dom > Dom

test.js

const puppeteer = require('puppeteer');
const url = process.env.URL || 'https://lit-element.polymer-project.org/';

(async () => {
    const browser = await puppeteer.launch();
    const page = await browser.newPage();

    await page.goto(url);
    await page.evaluate(() => {
		// loop through elements and copy shadow to inner
        for (let element of document.getElementsByTagName('*')) {
            if (element.shadowRoot) element.innerHTML = element.shadowRoot.innerHTML;
        }
    });
    let bodyHTML = await page.content();
    console.log(bodyHTML);
    await browser.close();
})();