I really like being able to run a little Javascript on a page, as a treat. Here’s a little lightweight “bookmarklets toolset” I’m using these days.
https://martymcgui.re/2023/05/23/a-little-bookmarklets-toolset/
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A little "bookmarklets toolset"
Browser bookmarks can run little bits of javascript on the current page if you use a "javascript:" URL. Folks often refer to these as "bookmarklets". (I wish they worked well in mobile browsers like iOS Safari, but that's a rant...)