In order to get the current page HTML source code (i.e. not the source code received from the server, but the currently loaded source code including Javascript modifications), use
await page.content()
Full example based on Puppeteer minimal example:
// Minimal puppeteer get page HTML source code example const puppeteer = require('puppeteer'); (async () => { const browser = await puppeteer.launch(); const page = await browser.newPage(); await page.goto('https://techoverflow.net', {waitUntil: 'domcontentloaded'}); // Wait for 5 seconds console.log(await page.content()); // Take screenshot await browser.close(); })();