Bookmarklets are an under appreciated part of web browsing. Here's one to tell you if the current article you are reading is posted on HN so you can read the comments:
I don't but they're pretty easy to explain. Create a new bookmark. Give it a name. In the url field instead of a standard url in the form "https://website.com" you put JavaScript in the form "javascript:(function(){...})();
They're bookmark buttons that execute Javascript on click. You need to put semi colons at the end of all lines since they don't preserve new lines. Bookmarklets should validate the URL if they are specific to a website or page. For larger ones, keep a source file since editing a single line of Javascript is not fun.
