JavaScript Prettify
Format and beautify JavaScript code with professional style guides. Choose from Standard, Airbnb, or Google presets, or customize formatting options. Includes syntax validation, format-on-paste, and side-by-side diff viewer.
Formatting Style Guide
Options
Recommended Settings
Style Guide Presets
- •Standard: Loose formatting, spaces after functions, 2-space indent
- •Airbnb: Strict style with 100-char line limit, breaks chained methods
- •Google: Clean style with K&R braces, no line length limit
- •Custom: Full control over all 15+ formatting options
Best Practices
- •Enable syntax validation to catch errors before formatting
- •Use format-on-paste for quick cleanup of external code
- •Check the diff viewer to understand formatting changes
- •Start with a preset, then customize if needed
Pro Tips
- •Format-on-paste is perfect for cleaning up minified code quickly
- •The diff viewer highlights exactly what changed during formatting
- •Airbnb preset enforces 100-character line limits for readability
- •Statistics show how many indentation and spacing issues were fixed
Most Popular
Most users choose Standard or Airbnb presets with format-on-paste enabled
When to Use This Tool
Transform compressed, single-line JavaScript back into readable, properly formatted code. Perfect for debugging minified libraries, examining production code, or understanding third-party scripts. Automatically restores indentation, line breaks, and spacing for easy comprehension.
Recommended: Debugging
Standardize code formatting across your team or project using industry-standard style guides (Standard, Airbnb, Google). Ideal for code reviews, refactoring legacy code, or preparing code for version control. Ensures consistent indentation, brace placement, and spacing throughout your codebase.
Recommended: Team Development
Format code examples for tutorials, documentation, Stack Overflow answers, or GitHub gists. Makes code more readable for others to learn from and easier to copy into projects. Automatically applies professional formatting standards that enhance code comprehension and reduce cognitive load.
Recommended: Education & Sharing
How It Works
Paste or type JavaScript code into the input area
Select a style guide preset (Standard/Airbnb/Google) or choose Custom
Optionally enable 'Format on paste' for automatic formatting
Tool validates JavaScript syntax before formatting
Click 'Format Code' to beautify your JavaScript
Indentation, spacing, and line breaks are normalized
Brace style and operator positioning are applied
Statistics show formatting changes and impact
Toggle 'Show Diff' to see before/after comparison
Copy formatted code or download as .js file
100% Private
Files never leave your device. All processing happens locally in your browser.
Lightning Fast
Powered by Client-side JavaScript with js-beautify library for optimal performance on modern browsers.
Open Source
Built with verified, open-source libraries. Fully transparent.
Frequently Asked Questions
What's the difference between the style guide presets?
Standard: Uses 2-space indentation with spaces after function keywords and loose formatting. Airbnb: Stricter formatting with 100-character line limit, breaks chained methods, and includes trailing newlines. Google: Similar to Airbnb but without line length limits and slightly different spacing rules. All three use 2-space indentation and K&R brace style (opening brace on same line).
Will formatting change how my code works?
No, formatting only changes whitespace, indentation, and code layout without modifying logic or functionality. Your code will execute identically before and after formatting. The tool validates JavaScript syntax before formatting to ensure the code is valid. However, if you rely on automatic semicolon insertion (ASI), be aware that adding line breaks might affect behavior in edge cases.
Can I customize the formatting options?
Yes! Select 'Custom' preset to access 15+ formatting options including indent size, brace style, spacing rules, line break behavior, operator positioning, and more. You can fine-tune indentation (2/4 spaces or tabs), control how braces and parentheses are formatted, set maximum line length, and configure method chaining style. Start with a preset and switch to Custom to tweak specific options.
What does 'Format on paste' do?
When enabled, code is automatically formatted as soon as you paste it into the input area. This is useful when quickly cleaning up code from external sources like minified files, console logs, or code snippets from websites. The formatting happens instantly using your selected preset. You can toggle this feature on/off based on your workflow preference.
Why is syntax validation important?
Syntax validation prevents formatting broken or incomplete JavaScript code, which could produce incorrect or misleading results. The tool checks for valid JavaScript syntax before formatting by attempting to parse your code. If syntax errors are detected, you'll see a clear error message indicating what needs to be fixed. This ensures the formatter only processes valid code and doesn't hide bugs behind pretty formatting.
Can I format minified code?
Absolutely! This tool excels at reformatting minified JavaScript back into readable code. It restores proper indentation, adds line breaks, spaces operators correctly, and makes the code structure clear. However, be aware that variable/function names in minified code (like 'a', 'b', 'c') won't be renamed to meaningful names - only the formatting/whitespace is changed. For best results with very large minified files, consider processing in smaller chunks.
Is my code safe and private?
Absolutely! All JavaScript formatting happens entirely in your browser using client-side JavaScript. Your code is never sent to any server, uploaded anywhere, or stored. The js-beautify library runs 100% locally, ensuring complete privacy and security for your proprietary source code. Even the syntax validation happens client-side using JavaScript's built-in parsing capabilities.