Why has no one made a Breaking Bad bookmarklet that highlights elemental symbols in text on web pages?
— Jason Kottke (@jkottke) September 24, 2013
Make a new bookmark with this URL:
javascript:var e=document.createElement("script");e.type = "text/javascript";e.src = "https://aprescott.com/files/breakingbad.js/bookmarklet.js";document.getElementsByTagName('head')[0].appendChild(e);
(It relies on a file hosted at aprescott.com, so no promises about this working indefinitely into the future. :))
Use the contents of bookmarklet.js as the URL of a bookmarklet. Make sure to put javascript: in front of it. It won't rely on any external server, but you won't get any changes if the script updates.
Almost all the functionality of this rests basically on James Padolsey's find and replace library.