Is it possible to know the name of a file that is being downloaded or to set a name before download?

Question

I'm downloading a ton of files using puppeteer, but I need to know each file's name before or after download is complete. Watching the folder for file change doesn't solve my problem, due to lots of processes downloading files at the same time and having now way to match them.

I've been trying to set a custom path for download for each file, but Puppeteer does something weird that some downloads go to that folder and others to /Downloads.

So, I would like to know if there's a way to know the name before download or to set the name of the file before downloading. This way I can properly match it through code.

Note: files are downloaded via JS i.e. when a button is clicked. No way to know file name via scraping due to it being auto-generated.

Answer 1

If the download is triggered by the page, this is done by using the Content-Disposition header. Very likely, the header also includes the file name as part of the header.

Example

Below, an example for the header:

Content-Disposition: attachment; filename="name_of_download.ext"

In order to read the filename, you can therefore check out the name of the file by looking at response.headers(). In the following example I'm using a regular expression after that to extract the file name:

const contentDisposition = response.headers()['content-disposition'];
const matchFilename = contentDisposition.match(/filename="(.*)"/);
if (matchFilename) {
  const filename = matchFilename[1];
}

Non-ASCII characters

Depending on the files you are downloading, you also might want to check out this stackoverflow answer regarding the encoding for non-ASCII file names.