#javascript #WordPress #Snippet #API

I have a "snippet" code
javascript:(()=>{window.open('https://spinka.tepewu.pl/wp-admin/post-new.php?in_reply_to='+encodeURIComponent(window.location.href));})();

which produces a specific type of post "in reply to" with just an URL embedded.

I assume that the code calls some API function and can pass some parameters to it.
Please somebody point me to a resource where I could learn how to create a post with a format of my choice, automatically embedding, say, an original title, header picture, and lead/abstract.

The use case is to aggregate singular posts into our climate infokiosk at #SPINKa