How to extract links which are available at multiple web pages or open tabs from the same websites?

Not entirely sure what you're looking for, but you could use jQuery.

var links = [];
$('a').each(function() {
   links.push( this.href ); 
   // output of links: ['http://www.google.com', 'http://www.dictionay.com']
   // According to comment
   // if you need each link separately then
   // may try like

   var href = this.href;
   console.log(href);
});

That script will print every link that is found on the page out to the browser's console.log.

I got the basic script at javascript - get all the links in a page using jquery - Stack Overflow[^] and then slightly altered it.

If you press F12 in your browser right now it'll open Dev Tools (Chrome, Edge). You can then copy the code and paste it into the Console and run it right here on this page.

You can see a snapshot of where I ran it on this page at : https://i.stack.imgur.com/V7Zvr.png

I know you only want the PDFs, but you can alter the script from here.