How can i get source from a minified javascript file?

Question

I used online YUI Compressor for minifying my javascript file... Now i got minified version of it but i lost the source as i uploaded the source javascript file without taking a copy of it...

• How can i get source from a minified javascript file?

Answer 1

You will have to work hard, but as a starting point I would recommend you to reformat and reindent the code, there are out there some tools to do it:

• JavaScript unpacker and beautifier
• JavaScript Beautifier

That as I said, will give you a starting point, you will need to know the code well to rename your variables and functions properly.

The last option would be to consider a rewrite, which if you know exactly what your script is meant to do, can take less time than refactoring the minified source...

And at last but not least I would recommend you to work always with a version control system and do backups often...

Answer 2

Minified JS file is the source code in fact. It's just highly obfuscated. You can, for example, load this file into Aptana editor and hit ctrl+shift+f to format the source. Or use any other source code formater.

You will get your code structure back, but the variable/function/property names are lost forever.

Hard lesson :)

Answer 3

I've used both the aforementioned

• JavaScript unpacker and beautifier
• JavaScript Beautifier

but i find the built-in Chrome Pretty print function in the Developer Tools to have been the the most consistent.

it's under the Scripts tab, in the icon menu alongside Pause on debug, Show/hide console, and Window docking

Answer 4

Here is an example where the referenced file is a minified file and automagically transformed into something legible:

http://prettydiff.com/?m=beautify&s=http://prettydiff.com/prettydiff.js