Change Content-Disposition filename with userscript from a Post

Question

I would like to change the file name of a downloaded file from Submit that uses Content-Disposition: attachment; filename=Reports.csv

I would like to Download that file with a preset file name Content-Disposition: attachment; filename=AnyFileName.csv

I would need it to be userscript friendly

The Download is Post and the content it returns is Content-Type: application/octet-stream; charset=UTF-8

I need it to change the filename of the download file

Answer 1

That's not gonna be easy at all. To do this you will have to:

• send the form properly using either XMLHttpRequest or fetch API
• After sending, retrieve the file data as Blob. You need to use responseType to request Blob
• Use URL.createObjectURL to create downloadable data URL

• Create link to allow download:

  <a href="${YOUR_DATA_URL}" download="AnyFileName.csv">Download</a>
  

• Dispatch a click on that link
• Wait a bit (few ms) and then free the memory using URL.revokeObjectURL

I'm sory, it's probably much more work than you expected. Good luck. You may alternatively consider some add-on or program that tampers with the HTML headers for that particular site.

It would be much easier if you could use the download attribute on <form>, but that's not possible.