You were able to build a list of controversial webpages (to compare them with my browser history), put to your css file that a:visited color: red; (just an example) and check with javascript which links have foreground color red - and voilaa. You know what pages I have in my history.

You need to save data to localstorage or something like that instead. And you can only save those clicks which are made from hackernews site... not populate it from browser history.