How to download PDF blob using puppeteer? - node.js

Question

When the download button is clicked, a new tab is opened where the user can view a PDF statement.
This new tab has a URL starting with blob:, e.g.: blob:https://some-domain.com/statement-id.
How could I download this PDF statement to the file system?
Note: I'm using { headless: false } mode.

Answer 1

Trying to simulate the case:
import puppeteer from 'puppeteer';
import { writeFileSync } from 'fs';
// Minimal PDF from https://github.com/mathiasbynens/small#documents
const minimalPdf = `%PDF-1.
1 0 obj<</Pages 2 0 R>>endobj
2 0 obj<</Kids[3 0 R]/Count 1>>endobj
3 0 obj<</Parent 2 0 R>>endobj
trailer <</Root 1 0 R>>`;
const browser = await puppeteer.launch({ headless: false, defaultViewport: null });
try {
const [page] = await browser.pages();
await page.goto('http://example.com/');
await page.evaluate((pdf) => {
const url = URL.createObjectURL(new Blob([pdf], {type: 'application/pdf'}));
window.open(url);
}, minimalPdf);
const newTarget = await page.browserContext().waitForTarget(
target => target.url().startsWith('blob:')
);
const newPage = await newTarget.page();
const blobUrl = newPage.url();
page.once('response', async (response) => {
console.log(response.url());
const pdfBuffer = await response.buffer();
console.log(pdfBuffer.toString());
console.log('same:', pdfBuffer.toString() === minimalPdf);
writeFileSync('minimal.pdf', pdfBuffer);
});
await page.evaluate((url) => { fetch(url); }, blobUrl);
} catch(err) { console.error(err); } finally { /* await browser.close(); */ }