Monday, June 11, 2012

Online Tool to Unminify / Decompress JavaScript

Are there any 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 (like with compression or packing) should theoretically not be an issue.

Source: Tips4all


  1. You can use this :
    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 :

  2. Chrome developer tools has this feature built-in. Bring up the developer tools (pressing F12 is one way), in the Scripts 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)

  3. Can't you just use a javascript formatter ( ?

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

  5. 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!";

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

  6. As an alternative (since I didn't know about 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)


  7. I'm not sure if you need source code. There is a free online JavaScript formatter at

  8. Try this one, with code coloration:

  9. 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.

  10. click on these link for JS deminification. That will install on FF as extension that help you in debugging js at runtime.

  11. 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.