How to Generate PDFs from Single Page Applications with Puppeteer?

Generating PDFs from Single Page Applications with Puppeteer

Building a single page application (SPA) presents challenges when it comes to generating PDFs because the content is loaded dynamically. This article addresses the issue of ensuring the page is fully loaded before exporting a PDF.

Approach:

The key to solving this problem lies in waiting for the page to load completely. Instead of guesstimating with fixed delays (e.g., await page.waitFor(2000);), we can utilize Puppeteer's page.waitForNavigation() method.

Implementation:

To wait for the page to load before generating the PDF, use the following code:

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

This will pause execution until the page has finished loading and all network activity has ceased.

Additional Considerations:

• waitForSelector(): If there is a specific element that needs to be rendered before the PDF is generated, consider using page.waitForSelector() to ensure its visibility:

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

• waitForNetworkIdle() vs. waitForNetworkIdle2(): Puppeteer offers two variants of waitUntil: networkidle0 and networkidle2. networkidle0 waits for all network requests to complete, while networkidle2 waits for a longer period, ensuring that all post-loading tasks have settled.

Conclusion:

By utilizing page.waitForNavigation() and, optionally, page.waitForSelector(), you can ensure that your PDFs are generated only when the page is completely loaded, accurately capturing the dynamic content of single page applications.

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