How to Ensure Page Completion Before Generating PDFs with Puppeteer?

Generating PDFs with Puppeteer: Waiting for Page Completion

When creating PDFs from web pages using Puppeteer, it's crucial to wait until the page is fully loaded to ensure the completeness and accuracy of the generated document. Let's delve into how to achieve this without resorting to manual delays.

The page.waitForNavigation() method provides a reliable way to wait for page navigation events, including the initial page load. By using the networkidle0 option, we specify that the function should wait until there are no more active network connections.

<code class="javascript">await page.goto(fullUrl, {
  waitUntil: 'networkidle0',
});</code>

Once the page is loaded, we can fill out the login form and submit it.

<code class="javascript">await page.type('#username', 'scott');
await page.type('#password', 'tiger');
await page.click('#Login_Button');</code>

Next, we can add an additional waitForNavigation() call to ensure that the login process is complete.

<code class="javascript">await page.waitForNavigation({
  waitUntil: 'networkidle0',
});</code>

Finally, we can proceed with generating the PDF.

<code class="javascript">await page.pdf({
  path: outputFileName,
  displayHeaderFooter: true,
  headerTemplate: '',
  footerTemplate: '',
  printBackground: true,
  format: 'A4',
});</code>

If you encounter cases where certain dynamic content needs to be included in the PDF, you can complement this approach with page.waitForSelector() to wait for the specific element to appear on the page before generating the PDF.

<code class="javascript">await page.waitForSelector('#example', {
  visible: true,
});</code>

By utilizing these techniques, you can ensure that Puppeteer waits for the page to fully load before generating the PDF, resulting in comprehensive and accurate document generation.

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