Are there any command line scripts and/or online tools that can reverse the effects of minification similar to how Tidy can clean up horrific HTML?
(I'm specifically looking to unminify a minified JavaScript file, so variable renaming might still be an issue.)
You can use this : http://jsbeautifier.org/ But it depends on the minify method you are using, this one only formats the code, it doesn't change variable names, nor uncompress base62 encoding.
edit: in fact it can unpack "packed" scripts (packed with Dean Edward's packer : http://dean.edwards.name/packer/)
Try this one, with code coloration:
http://labs.swelen.com/tools/javascript/beauty.html
click on these link for JS deminification. That will install on FF as extension that help you in debugging js at runtime.
https://addons.mozilla.org/en-US/firefox/addon/javascript-deminifier/eula/141018?src=dp-btn-primary
Chrome developer tools has this feature built-in. Bring up the developer tools (pressing F12 is one way), in the Sources tab, the bottom left bar has a set of icons. The "{}" icon is "Pretty print" and does this conversion on demand.
UPDATE: IE9 "F12 developer tools" also has a "Format JavaScript" feature in the Script tab under the Tools icon there. (see Tip #4 in F12 The best kept web debugging secret)
If one is in JS possibility of using Firefox is more. And if its Firefox add on is for rescue. Following one is particularly useful.
https://addons.mozilla.org/en-US/firefox/addon/phoenix/