Developer Tools
Beautify JavaScript
Transform pasted text with the javascript beautifier and copy the cleaned output.
Direct Answer
Use the JavaScript Beautifier when you need to read minified, bundled, or mangled JavaScript, for example while debugging a production error from a stack trace pointing at a single-line file. It reinserts line breaks, indentation, and spacing around minified code without changing what the code actually does.
Reading Minified Production JavaScript
Most JavaScript running in a browser was never meant to be read as shipped, and beautifying is often the only way in without a source map.
- Paste a single-line bundle to restore line breaks, indentation, and spacing.
- Useful when a stack trace points at a minified file with no attached source map.
- It will not undo variable name mangling; only a matching source map can map names back to the original.
- Nested callbacks and chained method calls become visually traceable once expanded.
What Beautifying Cannot Undo
Beautifying only restores whitespace; several other transformations a minifier applies are permanent.
- Variable and function names already shortened by a minifier.
- Logic already restructured into denser forms, like a ternary replacing an if and else block.
- Dead code or unused branches already removed by a build step.
- Anything a source map would normally restore, since beautifying and source maps solve the readability problem differently.
How to Use Javascript Beautifier
- Paste or type your content into the input box.
- The transformed result appears instantly in the result panel below.
- Click Copy result to copy the output to your clipboard.
- Download .txt saves the transformed text as a file.
- Reset clears everything and lets you start over.
Reference
| Feature | Details |
|---|---|
| Purpose | Transform pasted text into a cleaner or different format. |
| Input | Text, lines, lists, or copied content. |
| Result | Transformed text ready to copy or download. |
| Best for | Cleanup, formatting, list preparation, and copy-paste workflows. |
| Category | Developer Tools |
| Works on | Desktop, tablet, and mobile browsers |
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Frequently Asked Questions
Why is the JavaScript from a production site all on one line?
Bundlers and minifiers strip whitespace and line breaks to reduce file size before deployment, so viewing a bundle's source in dev tools shows one long, unreadable line. Beautifying reinserts line breaks and indentation so you can actually read the logic instead of scrolling sideways forever.
Can beautifying restore my original variable names after minification?
No, if the minifier renamed variables to short names to save space, that renaming is permanent, and beautifying only adds whitespace back. The original names are gone unless you have a matching source map, which is a completely different mechanism for mapping minified code back to source.
What is a source map, and does beautifying replace the need for one?
A source map is a separate file that maps positions in minified code back to the exact line, column, and file in the original source, letting a debugger show you the real source directly. Beautifying a minified file without a source map gives you readable but renamed code, while a source map gives you the actual original file, so the two solve a similar problem in very different ways.
Will beautifying add semicolons my code is missing?
Some beautifiers will insert semicolons at the end of statements based on where JavaScript's automatic semicolon insertion would already apply them implicitly, but this is a formatting choice, not a fix. Code that relies on automatic semicolon insertion already runs correctly without explicit semicolons; beautifying just makes those implicit statement boundaries visible in the source.
Does beautifying JavaScript check for syntax errors?
Beautifying generally requires the code to already be syntactically valid, since the tool has to parse it to know where statements and blocks begin and end. If the code has an actual syntax error, beautifying will fail or produce broken output rather than silently formatting around the mistake.
Why does beautified minified code still look confusing after formatting?
Minifiers also mangle variable and function names down to single letters and often flatten logic into fewer, denser expressions, such as a ternary in place of an if and else block. Beautifying restores readable line breaks and indentation but cannot undo mangled names or restructure dense expressions back into their original, more verbose form.
Can I beautify an immediately invoked function expression safely?
Yes, beautifying only affects whitespace and indentation, so an immediately invoked function expression keeps its exact wrapping and execution behavior. It will just be indented and spread across multiple lines instead of appearing compressed onto one.
Does beautifying affect where a strict mode directive needs to sit?
No, a strict mode directive must remain the first statement in a file or function to take effect, and beautifying does not move statements around, only adding whitespace between them, so its position and effect are unchanged.