Tool to Unminify / Decompress JavaScript [closed]

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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.)

Revkah answered 4/5, 2009 at 21:20 Comment(5)

For those of you who may not be aware, minification changes internal variable names to a single letter and removes code comments. Undoing these changes cannot be automated. – Penthouse 22/2, 2013 at 16:33

@DanielAllenLangdon Good point. I've edited the question so it no longer implies that minification does not change variable names. – Revkah 3/4, 2013 at 16:24

FWIW... just found JS NICE jsnice.org – Revkah 2/6, 2014 at 22:10

marcusjenkins.com/linux/… worked well for me. – Ericaericaceous 8/3, 2015 at 11:7

For @DanielAllenLangdon: jsnice.org can unminify and de-obfuscate even 30k angularjs code. – Leeway 4/9, 2015 at 1:9

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511

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/)

Georgy answered 4/5, 2009 at 21:24 Comment(4)

did you mean base64 encoding? I've never heard of base62 encoding... – Terrorist 4/5, 2009 at 22:25

Nope, I said base 62 : dean.edwards.name/packer and en.wikipedia.org/wiki/Base_62 – Ramulose 5/5, 2009 at 6:25

is there such a thing as a tool that "changes variable names" and is still aware of JS syntax to not break the code? – Columbary 7/9, 2009 at 7:57

Fantastic. I just solved my problem, then emailed the author of the framework with the exact fix. – Pacha 8/7, 2010 at 11:45

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161

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)

Amide answered 22/8, 2011 at 15:22 Comment(6)

For the particular .js I was trying to un-minify, this method worked the best, cheers. – Kelbee 6/10, 2011 at 17:33

This is now in the "Sources" tab, not the Scripts tab. – Parke 24/9, 2012 at 21:44

@mhenry1384: Yes, Chrome did rename the tab. I updated the answer accordingly. – Amide 24/9, 2012 at 22:0

YES!! (our app does not have a debug/dev mode for js that I am aware of -- we thankfully do not shorten/transform variable names.) – Node 17/5, 2013 at 18:11

Just a heads-up: Chrome sometimes messes up the JavaScript code. For instance, if (a) /regex/.match(foo); is pretty printed as if (a)\n / /regex/ .\nmatch(foo); which is a syntax error. – Speculum 9/1, 2015 at 20:1

Firefox does this as well. On the current version, you right-click on the tab for the file you want to examine and select Pretty Print source. – Brogan 26/6, 2018 at 10:58

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Got it! JSBeautifier does exactly this, and you even have options for the auto-formatting.

Handout answered 22/6, 2009 at 16:26 Comment(3)

stackoverflow-then-google instead of google-then-stackoverflow? :)))) – Being 22/6, 2009 at 16:29

I did the google for "javascript formatter online" – Stans 22/6, 2009 at 16:29

This FireFox plugin uses JSBeautifier to un-minify javascript so you can then set breakpoints on lines in FireBug's js debugger!!: addons.mozilla.org/en-US/firefox/addon/javascript-deminifier – Attain 28/1, 2011 at 0:44

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Can't you just use a javascript formatter (http://javascript.about.com/library/blformat.htm) ?

Heterolecithal answered 4/5, 2009 at 21:25 Comment(3)

+1 for answer that also works. fabien just happened to reply first – Revkah 4/5, 2009 at 21:30

This only answer the "decompress" part of the question. – Columbary 7/9, 2009 at 7:58

Nope this is not working good. It break the code... :( – Cynthy 30/4, 2014 at 14:25

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In Firefox, SpiderMonkey and Rhino you can wrap any code into an anonymous function and call its toSource method, which will give you a nicely formatted source of the function.

toSource also strips comments.

E. g.:

(function () { /* Say hello. */ var x = 'Hello!'; print(x); }).toSource()

Will be converted to a string:

function () {
    var x = "Hello!";
    print(x);
}

P. S.: It's not an "online tool", but all questions about general beautifying techniques are closed as duplicates of this one.

Descant answered 3/10, 2011 at 12:46 Comment(2)

Interesting. I asked the question 2.5 years ago so I feel it's too late to edit the title, but I still like seeing both online and offline options. Thanks for chiming in. +1 – Revkah 3/10, 2011 at 19:55

Doesn't seem to work any more on firefox – Aged 28/9, 2020 at 12:56

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10

If you have a Mac and TextMate - An easy alternative for formatting Javascript is:

Open the file with Textmate.
Click on > Bundles > JavaScript > Reformat Document
Crack open a beer.

Faulkner answered 11/10, 2011 at 22:53 Comment(1)

Beer being served right now :) – Tarra 9/12, 2011 at 16:48

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7

Most of the IDEs also offer auto-formatting features. For example in NetBeans, just press CTRL+K.

Conchology answered 21/6, 2011 at 17:9 Comment(0)

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5

As an alternative (since I didn't know about jsbeautifier.org until now), I have used a bookmarklet that reenabled the decode button in Dean Edward's Packer.

I found the instructions and bookmarklet here.

here is the bookmarklet (in case the site is down)

javascript:for%20(i=0;i<document.forms.length;++i)%20{for(j=0;j<document.forms[i].elements.length;++j){document.forms[i].elements[j].removeAttribute(%22readonly%22);document.forms[i].elements[j].removeAttribute(%22disabled%22);}}

Jape answered 21/9, 2009 at 22:57 Comment(0)

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I'm not sure if you need source code. There is a free online JavaScript formatter at http://www.blackbeltcoder.com/Resources/JSFormatter.aspx.

Fructuous answered 23/5, 2011 at 3:18 Comment(0)

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Try this one, with code coloration:

http://labs.swelen.com/tools/javascript/beauty.html

Package answered 22/10, 2011 at 12:59 Comment(0)

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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

Make answered 18/1, 2012 at 5:52 Comment(0)

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5

Similar to Stone's answer, but for Windows/.NET developers:

If you have Visual Studio and ReSharper - An easy alternative for formatting Javascript is:

Open the file with Visual Studio;
Click on ReSharper > Tools > Cleanup Code (Ctrl+E, C);
Select "Default: Reformat code", and click OK;
Crack open a beer.

Spite answered 13/6, 2012 at 11:53 Comment(0)

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4

Despite its miles-away-from-being-pretty interface, JSPretty is a good, free and online tool for making javascript source codes human-readable. You can enforce your preferred type of indentation and it can also detect obfuscation.

Brodeur answered 13/8, 2013 at 12:49 Comment(0)

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3

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/

Fettling answered 29/4, 2011 at 8:34 Comment(0)

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3

Pretty Diff will beautify (pretty print) JavaScript in a way that conforms to JSLint and JSHint white space algorithms.

Bulwark answered 29/7, 2012 at 10:4 Comment(1)

It's ironic the site is so un-pretty, but this is a cool tool. – Revkah 30/7, 2012 at 21:48

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Wasn't really happy with the output of jsbeautifier.org for what I was putting in, so I did some more searching and found this site: http://www.centralinternet.com.br/javascript-beautifier

Worked extremely well for me.

Desolate answered 18/11, 2013 at 20:21 Comment(0)

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http://unminify.appspot.com/ Great tools for unminify javascript and json

Plauen answered 28/12, 2012 at 3:56 Comment(0)

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