Puppeteer wait until page is completely loaded

You can use page.waitForNavigation() to wait for the new page to load completely before generating a PDF:

await page.goto(fullUrl, {
  waitUntil: 'networkidle0',
});

await page.type('#username', 'scott');
await page.type('#password', 'tiger');

await page.click('#Login_Button');

await page.waitForNavigation({
  waitUntil: 'networkidle0',
});

await page.pdf({
  path: outputFileName,
  displayHeaderFooter: true,
  headerTemplate: '',
  footerTemplate: '',
  printBackground: true,
  format: 'A4',
});

If there is a certain element that is generated dynamically that you would like included in your PDF, consider using page.waitForSelector() to ensure that the content is visible:

await page.waitForSelector('#example', {
  visible: true,
});

Sometimes the networkidle events do not always give an indication that the page has completely loaded. There could still be a few JS scripts modifying the content on the page. So watching for the completion of HTML source code modifications by the browser seems to be yielding better results. Here's a function you could use -

const waitTillHTMLRendered = async (page, timeout = 30000) => {
  const checkDurationMsecs = 1000;
  const maxChecks = timeout / checkDurationMsecs;
  let lastHTMLSize = 0;
  let checkCounts = 1;
  let countStableSizeIterations = 0;
  const minStableSizeIterations = 3;

  while(checkCounts++ <= maxChecks){
    let html = await page.content();
    let currentHTMLSize = html.length; 

    let bodyHTMLSize = await page.evaluate(() => document.body.innerHTML.length);

    console.log('last: ', lastHTMLSize, ' <> curr: ', currentHTMLSize, " body html size: ", bodyHTMLSize);

    if(lastHTMLSize != 0 && currentHTMLSize == lastHTMLSize) 
      countStableSizeIterations++;
    else 
      countStableSizeIterations = 0; //reset the counter

    if(countStableSizeIterations >= minStableSizeIterations) {
      console.log("Page rendered fully..");
      break;
    }

    lastHTMLSize = currentHTMLSize;
    await page.waitFor(checkDurationMsecs);
  }  
};

You could use this after the page load / click function call and before you process the page content. e.g.

await page.goto(url, {'timeout': 10000, 'waitUntil':'load'});
await waitTillHTMLRendered(page)
const data = await page.content()

In some cases, the best solution for me was:

await page.goto(url, { waitUntil: 'domcontentloaded' });

Some other options you could try are:

await page.goto(url, { waitUntil: 'load' });
await page.goto(url, { waitUntil: 'domcontentloaded' });
await page.goto(url, { waitUntil: 'networkidle0' });
await page.goto(url, { waitUntil: 'networkidle2' });

You can check this at puppeteer documentation: https://pptr.dev/#?product=Puppeteer&version=v11.0.0&show=api-pagewaitfornavigationoptions

I always like to wait for selectors, as many of them are a great indicator that the page has fully loaded:

await page.waitForSelector('#blue-button');

Wrap the page.click and page.waitForNavigation in a Promise.all

  await Promise.all([
    page.click('#submit_button'),
    page.waitForNavigation({ waitUntil: 'networkidle0' })
  ]);