You do not have control to do this, plus this is expected behaviour and there is nothing you need to do.
Screen reader users will go out of the active screen using shortcut keys if they wish to access the file.
Other considerations as you said "button" in your question
You should not use a <button>
element to generate a file. File downloads should always be a hyperlink (<a>
).
If the document requires variables to be passed and you are able to pass them via a GET request then the hyperlink href
should be the URL + GET parameters.
The advantage of this for everyone is that they can middle click to open the document in a new window (or right click and choose "open in new window" etc.), plus it works without JavaScript and is easily indexed by Search Engines.
Also adding the download
attribute to a hyperlink has some advantages, especially as in some screen readers it gets signalled to users that this link will download a document.
When creating a download link you should state the document type (pdf, word etc.) and document size for accessibility. You can do this with visually hidden text if your design does not allow for it.
I have written a reasonably in-depth answer on how to add the file size and file type info for screen readers here. About 70% of it is relevant to you.