# How can I change what happens when I click on a pdf-tools link?

I read pdfs with pdf-tools, but I think what I'm asking may apply to more than pdf-tools alone.

In any case, as an example, some research paper pdfs have references with clickable links - say a link to the journal as in: http://journal-name.com/article-id. When the link is clicked, the browser opens up and redirects to the URL specified in the link.

So far so good. What I would like to know though, is if would be possible to have links redirect somewhere else. Instead of going to the journal website, I would like to know whether clicks could redirect to https://my-website.tw/http://journal-name.com/article-id instead (perhaps only when the link matches a regexp).

How would something in these lines be implemented?

I don't even know what function to change, because calling C-h k on a mouse press seems to show me a function that is completely irrelevant to following links.

The customizable option pdf-links-browse-uri-function holds a function that receives a string with the uri as an argument and should take the appropriate action, e.g., open the link in a browser.
You can define your own function and register it there with M-x customize-option.
The formulation of the title of your question "How can I change what happens when I click on a link?" is very general. It is even still quite involved if you narrow it down to pdf-tools.