How can I download a pdf file in puppeteer?

Between the click and the browser.close() is the delay of the download of the file from the server, right? Then it would be better to control the download request so that once you have it in memory, moving it from there to the one saved on the PC is direct. You could use a function like this:

const downloadFile = () => {
   return fetch('urlRequest', configRequest).then(res=>res.blob)
}

That function would return a promise with the blob of the file. Remember that to be able to do this function successfully you must carefully inspect the anatomy of the request that makes the equivalent click that you mentioned.

Then you could create a url with that blob:

const blob = await downloadFile()
const href = URL.createObjectURL(blob)

With that you can now assign it to the "href" attribute of an "ancor" elementwith "download" attribute. To then execute its click method and download to the pc, but since the data is already local, the process is immediate, so browser.close() will no longer beat you.

The download process would generally be something like this:

//... 
await page.evaluate(async () => {
   const downloadFile = () => fetch('url').then(res=>res.blob)
   const createURL = blob => URL.createObjectURL(blob)
   const saveFile = href => {
      const a = document.createElement('a')
      a.href = href
      a.download = 'descarga.txt' // pon la extensión correspondiente.
      a.click()
   }
   const mainDownload = async () => {
      const blob = await downloadFile()
      const href = createURL(blob)
      saveFile(href)
   }
   await mainDownload()
})
await browser.close();

However, for that do not forget to put before the download path with:

await page._client.send('Page.setDownloadBehavior', {
   behavior: 'allow',
   downloadPath: '/root/project/app/your_download/'
});

I haven't tested the code so maybe there is some syntax error, but the idea itself should work since these requests are usually recurring and this is usually the correct way or at least that's how we do it in my work.

Anyway, I hope I have helped you. Regards and)

I finally got around it using node-fetchand some utilities to write files.

// ...

const fs = require( 'fs' )
const util = require( 'util' )
const stream = require( 'stream' )

const fetch = require( 'node-fetch' )


// ...

await page.waitForSelector( field.download )
const fetchURL = await page.$eval( field.download, download => download.href )

// Manage permission download via async fetch
await ( async () => {

    // Download the pdf permission
    const response = await fetch( fetchURL )

    // Prepare streamline
    const streamPipeline = util.promisify( stream.pipeline )
    const writeStream = fs.createWriteStream( `${ config['download-path'] }/permisov-${ Date.now() }.pdf` )

    // Save file to disk
    streamPipeline( response.body, writeStream )

})()

field.downloadis my html selector which I import from an object.

Node-fetch: https://github.com/node-fetch/node-fetch

The other utilities are available in node.

I did what Darwin told me. Right now I have this but I have the same initial problem. Before saving the pdf file the browser closes

    await page._client.send('Page.setDownloadBehavior', {behavior: 'allow', downloadPath: '/Users/diego/Downloads'})
    await page.waitForSelector('a[id="linkpdf"]')
    console.log("downloading...")

    await page.evaluate( async () => {

        await ( async () => {
            const linkElement = document.querySelector( 'a[id="linkpdf"]' )
            const fetchURL = linkElement.href

            const response = await fetch( fetchURL )
            const blobFile = await response.blob()

            const newBlob = new Blob( [blobFile], { type: 'application/pdf' })
            const fileHref = URL.createObjectURL( newBlob )

            const saveTrigger = document.createElement( 'a' )
            
            saveTrigger.href = fileHref
            saveTrigger.download = `permiso-${ Date.now() }.pdf`
            saveTrigger.click()

        })().catch( e => console.error(e) )
    })

    console.log("downloaded!")
    await browser.close()
    console.log("exit")