How to Generate Reliable PDFs from Single-Page Applications Using Puppeteer?

Puppeteer: Reliable PDF Generation by Waiting for Page Completion

Many web-based applications face the issue of generating PDFs from web pages efficiently. Single-page applications, in particular, present challenges in this regard. This article addresses the problem and provides solutions for those using Puppeteer to generate PDFs.

Initial Attempts and Challenges

An initial approach may involve using page.waitFor('networkidle2') to wait until network activity has stabilized. However, for single-page applications, this method often fails to wait for the complete loading of the page, leading to truncated PDF documents.

Solution: Wait for Navigation

A more reliable solution is to employ page.waitForNavigation() to wait for the new page to load completely before generating a PDF:

<code class="python">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',
});</code>

This method ensures that the PDF is only generated after the entire navigation process is complete.

Waiting for Dynamic Elements

In instances where there are dynamically generated elements that need to be included in the PDF, page.waitForSelector() can be used to ensure that the content is rendered before proceeding:

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

By using these techniques, developers can generate PDFs from single-page applications with reliability, ensuring that all necessary content is captured in the document.

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