JavaScript Beautifier

Quick Start Guide

1. Paste Code: Copy your minified or messy JavaScript code into the input area
2. Configure Options: Choose indentation, quotes, semicolons, and other formatting preferences
3. Beautify: Click "Beautify Code" to format your JavaScript
4. Copy or Download: Use the output buttons to copy or download the formatted code
5. Try Examples: Click example buttons to see different formatting scenarios

What is JavaScript Beautification?

JavaScript beautification (also called formatting or pretty-printing) transforms minified, compressed, or poorly formatted JavaScript code into clean, human-readable code with proper indentation, spacing, and line breaks. It makes code easier to read, debug, and maintain.

Purpose: Code readability, debugging minified code, standardizing style Input: Minified, compressed, or messy JavaScript Output: Clean, properly indented, readable JavaScript Usage: Development, debugging, code review, team collaboration

Why Beautify JavaScript?

Development Benefits:

• Transform minified production code back to readable format
• Standardize code style across your team
• Make code reviews faster and more effective
• Debug third-party minified libraries
• Learn from obfuscated or compressed code
• Improve code maintainability

Common Scenarios:

• Unminifying production JavaScript for debugging
• Cleaning up automatically generated code
• Formatting code from online sources
• Standardizing legacy codebases
• Preparing code for documentation
• Teaching and learning JavaScript

Formatting Options Explained

Indentation

Indent Size:

• 2 spaces: Modern JavaScript standard (Prettier, Airbnb)
• 4 spaces: Traditional preference, more visual separation
• Tabs: Flexible, allows individual developer preferences

Indent Type:

• Spaces: Consistent across all editors and viewers
• Tabs: More efficient, customizable display width

When to use:

• 2 spaces: Modern web projects, React, Vue, Angular
• 4 spaces: Java-style conventions, older projects
• Tabs: Team preference, accessibility considerations

Semicolons

Options:

• Keep as-is: Preserve original semicolon usage
• Add missing: Insert semicolons where they're implied (ASI)
• Remove all: Remove all semicolons (modern style)

Examples:

// Keep as-is (preserves original)
const x = 5;
const y = 10

// Add missing
const x = 5;
const y = 10;

// Remove all
const x = 5
const y = 10

Recommendation: Use "Add missing" for safety, "Remove all" for modern style

Quotes

Options:

• Keep as-is: Preserve original quote style
• Single quotes: Convert to 'single quotes' (Prettier default)
• Double quotes: Convert to "double quotes" (JSON style)

Examples:

// Single quotes
const name = 'John'
const greeting = 'Hello, World!'

// Double quotes
const name = "John"
const greeting = "Hello, World!"

Recommendation: Single quotes for JS (most popular), double quotes for JSON compatibility

Trailing Commas

Options:

• None: No trailing commas
• ES5: Add to arrays and objects only
• All: Add to all multi-line structures (including function params)

Examples:

// None
const arr = [1, 2, 3]

// ES5 (objects and arrays)
const arr = [1, 2, 3,]
const obj = { a: 1, b: 2, }

// All (including function parameters)
function foo(
  param1,
  param2,
) {}

Recommendation: ES5 for broad compatibility, All for modern projects

Arrow Function Parentheses

Options:

• Avoid: Omit parens for single parameters: x => x * 2
• Always: Always use parens: (x) => x * 2

Examples:

// Avoid (cleaner for single params)
const double = x => x * 2
const add = (a, b) => a + b  // Required for multiple params

// Always (consistent style)
const double = (x) => x * 2
const add = (a, b) => a + b

Recommendation: Avoid for cleaner code, Always for consistency

Common Use Cases

1. Unminifying Production Code

Purpose: Debug minified JavaScript from production environments

Scenario: You need to debug an issue in production, but the JavaScript is minified and unreadable.

Before (minified):

function calc(a,b){return a+b}const arr=[1,2,3].map(x=>x*2);if(true){console.log("test")}

After (beautified with 2-space indent):

function calc(a, b) {
  return a + b
}
const arr = [1, 2, 3].map(x => x * 2);
if (true) {
  console.log("test")
}

2. Formatting Modern ES6+ Code

Purpose: Clean up arrow functions, destructuring, and modern syntax

Before:

const users=[{name:"John",age:30},{name:"Jane",age:25}];const names=users.map(u=>u.name);const filtered=users.filter(u=>u.age>26);

After:

const users = [
  { name: "John", age: 30 },
  { name: "Jane", age: 25 }
];
const names = users.map(u => u.name);
const filtered = users.filter(u => u.age > 26);

3. Cleaning Complex Object Structures

Purpose: Format nested configuration objects for readability

Before:

const config={server:{host:"localhost",port:3000,ssl:{enabled:true,cert:"/path/to/cert"}},database:{type:"postgres",connection:{host:"db.example.com"}}};

After:

const config = {
  server: {
    host: "localhost",
    port: 3000,
    ssl: {
      enabled: true,
      cert: "/path/to/cert"
    }
  },
  database: {
    type: "postgres",
    connection: {
      host: "db.example.com"
    }
  }
};

4. Formatting React/JSX Components

Purpose: Clean up React component code

Before:

const Button=({onClick,children})=>{const [count,setCount]=useState(0);return <button onClick={()=>{setCount(count+1);onClick()}}>{children}</button>};

After:

const Button = ({ onClick, children }) => {
  const [count, setCount] = useState(0);
  return (
    <button
      onClick={() => {
        setCount(count + 1);
        onClick()
      }}
    >
      {children}
    </button>
  );
};

5. Standardizing Team Code Style

Purpose: Enforce consistent formatting across a team

Use Case: You have multiple developers with different coding styles. Use the beautifier with specific options (e.g., 2 spaces, single quotes, semicolons) to standardize all code.

Settings:

• Indent: 2 spaces
• Quotes: Single
• Semicolons: Add missing
• Trailing comma: ES5

6. Learning from Minified Libraries

Purpose: Study how popular libraries work by beautifying their code

Scenario: You want to understand how a third-party library works, but the npm package contains minified code.

Process:

1. Copy the minified code from node_modules
2. Beautify it to make it readable
3. Study the implementation
4. Learn new techniques and patterns

Features

Core Functionality

• Automatic Indentation: Properly indent nested blocks and functions
• Spacing Normalization: Add consistent spacing around operators
• Line Break Management: Insert line breaks for readability
• Comment Preservation: Keep all comments intact
• String Safety: Never modify content inside strings
• Multiple Format Options: Customize to match your style guide

Supported JavaScript Features

• ES6+: Arrow functions, destructuring, template literals
• Classes: ES6 class syntax with methods
• Async/Await: Modern asynchronous patterns
• JSX: React component formatting (basic)
• Object/Array Literals: Complex nested structures
• Functions: Regular, arrow, async, generator functions

Formatting Controls

Indentation:

• 2 spaces (default, most popular)
• 4 spaces (traditional)
• Tabs (flexible)

Quote Style:

• Keep original (default)
• Single quotes (modern standard)
• Double quotes (JSON-compatible)

Semicolons:

• Keep as-is (preserve original)
• Add missing (safe, explicit)
• Remove all (modern, clean)

Trailing Commas:

• None (minimal)
• ES5 (arrays/objects)
• All (including functions)

Arrow Functions:

• Avoid parens (x => x)
• Always parens ((x) => x)

Best Practices

1. Choose Consistent Settings

Pick formatting options that match your team's style guide:

Airbnb Style:

• Indent: 2 spaces
• Quotes: Single
• Semicolons: Add
• Trailing comma: ES5
• Arrow parens: Avoid

Standard Style:

• Indent: 2 spaces
• Quotes: Single
• Semicolons: Remove
• Trailing comma: ES5
• Arrow parens: Avoid

Prettier Default:

• Indent: 2 spaces
• Quotes: Double
• Semicolons: Add
• Trailing comma: ES5
• Arrow parens: Always

2. Test After Beautifying

Always test beautified code before using in production:

1. Beautify the code
2. Run your tests
3. Check for syntax errors
4. Verify functionality
5. Review manually for correctness

3. Use Source Maps for Debugging

When debugging minified production code:

1. Check if source maps are available
2. Use browser DevTools with source maps first
3. Use beautifier as fallback when maps unavailable
4. Compare beautified code with original when possible

4. Combine with Linters

For best results:

1. Beautify code first
2. Run ESLint or similar linter
3. Fix any remaining issues
4. Commit formatted code

5. Version Control Integration

Before committing:

• Beautify all modified JavaScript files
• Use same settings across team
• Add .editorconfig for consistency
• Consider pre-commit hooks

Technical Details

How Beautification Works

1. Parse input code character by character
2. Track context (in string, comment, etc.)
3. Identify blocks and nesting levels
4. Apply indentation based on nesting
5. Add spacing around operators
6. Insert line breaks at appropriate points
7. Apply quote and semicolon preferences
8. Output formatted code

Limitations

This is a basic beautifier:

• Uses character-by-character parsing (not full AST)
• May not handle all edge cases perfectly
• Works well for most common JavaScript patterns
• Not a replacement for Prettier or ESLint

For production projects, consider:

• Prettier: Full AST-based formatting
• ESLint --fix: Linting + auto-fixing
• js-beautify: More comprehensive beautifier
• dprint: Fast, configurable formatter

This tool is best for:

• Quick one-off formatting
• Debugging minified code
• Learning and education
• Simple formatting tasks

Supported Syntax

✅ Fully supported:

• Function declarations and expressions
• Arrow functions
• Object and array literals
• Template literals (basic)
• Comments (single-line and multi-line)
• ES6 classes
• if/else, loops, switch statements
• Variable declarations (const, let, var)

⚠️ Limited support:

• JSX (basic formatting only)
• Complex template literals
• Very deeply nested structures
• Regular expressions in complex contexts

Performance

Processing speed:

• Small files (<10KB): Instant
• Medium files (10-100KB): <1 second
• Large files (100KB-1MB): 1-3 seconds
• Very large files (>1MB): May be slow

Browser-based:

• All processing happens in your browser
• No server uploads or network delays
• Works offline after initial page load
• RAM usage: ~2-5MB per 100KB of code

Troubleshooting

Issue: Output looks wrong or broken

Possible causes:

1. Input code has syntax errors
2. Complex edge case not handled
3. String content being modified

Solutions:

• Check input code for syntax errors first
• Try different formatting options
• For complex code, use Prettier or js-beautify
• Report specific issues with examples

Issue: Code doesn't work after beautifying

Possible causes:

1. Original code had syntax errors hidden by minification
2. Semicolon insertion/removal broke code
3. Quote conversion affected string content

Solutions:

• Use "Keep as-is" for quotes and semicolons
• Test in small sections to isolate issues
• Compare with original carefully
• Use AST-based tools for critical code

Issue: Comments disappeared

This shouldn't happen - comments should be preserved. If you experience this:

1. Check if comments were in the original
2. Try beautifying just the section with comments
3. Report the issue with example

Issue: Performance is slow

For large files:

• Break into smaller chunks
• Use command-line tools (Prettier, js-beautify)
• Increase browser memory if possible
• Consider desktop tools for very large files

Browser Compatibility

Supported browsers:

• ✅ Chrome 90+ (recommended)
• ✅ Firefox 88+
• ✅ Safari 14+
• ✅ Edge 90+
• ✅ Opera 76+

Required features:

• ES6+ JavaScript support
• Clipboard API (for copy function)
• Blob API (for download)
• Modern CSS (for UI)

Works on:

• Desktop: Windows, macOS, Linux
• Mobile: iOS Safari, Chrome Android
• Tablets: iPad, Android tablets

Privacy & Security

Client-Side Processing

• 100% Local: All beautification in your browser
• No Uploads: Code never sent to any server
• No Storage: Nothing saved or cached
• No Tracking: No analytics on your code
• No Accounts: No login or registration required

Security Features

• Sandboxed: Runs in browser security sandbox
• No Execution: Code is never executed, only parsed
• Safe Parsing: Character-based, not eval-based
• No External Calls: No network requests during processing

Safe for Sensitive Code

• ✅ Proprietary code
• ✅ Client projects
• ✅ Production code
• ✅ Code with secrets (but remove before sharing!)
• ✅ Personal projects

Important: Always remove API keys, passwords, and secrets before beautifying code, just like you would before committing to version control.

Comparison with Other Tools

JavaScript Beautifier vs Prettier

JavaScript Beautifier (this tool):

• ✅ Browser-based, instant access
• ✅ Simple, straightforward options
• ✅ No installation required
• ✅ Privacy-focused (100% local)
• ❌ Basic parsing, not AST-based
• ❌ Limited advanced features

Prettier:

• ✅ Full AST parsing, perfect output
• ✅ Supports many languages
• ✅ Widely used in production
• ❌ Requires npm installation
• ❌ Command-line or editor integration
• ❌ Opinionated (fewer options)

When to use this tool: Quick formatting, debugging, learning, one-off tasks

When to use Prettier: Production projects, team collaboration, automated formatting

JavaScript Beautifier vs ESLint

This tool: Formatting only ESLint: Linting (finding bugs) + formatting with --fix

Use ESLint when: You want to catch bugs and enforce code quality Use this tool when: You just need to format code quickly

JavaScript Beautifier vs js-beautify

This tool: Web-based, simple, instant js-beautify: Command-line, more comprehensive, more options

This tool is better for: Quick browser-based formatting js-beautify is better for: Automation, scripting, advanced features

Integration Tips

Using Beautified Code in Projects

1. Copy to Editor:

• Beautify code
• Click "Copy Output"
• Paste into your code editor
• Save file

2. Download File:

• Beautify code
• Click "Download .js"
• Replace original file
• Test thoroughly

3. Combine with Git:

# Beautify code
# Then in terminal:
git diff  # Review changes
git add .
git commit -m "Format JavaScript code"

Setting Up Team Standards

1. Agree on settings:

• Document preferred indent size (e.g., 2 spaces)
• Choose quote style (e.g., single)
• Decide on semicolons (e.g., add)

2. Add to documentation:

• Include beautifier settings in README
• Add .editorconfig file
• Consider .prettierrc for Prettier

3. Code review checklist:

• Code properly indented
• Consistent quote style
• Consistent semicolon usage
• Clean, readable formatting

Quick Reference

Recommended Settings by Use Case

Debugging minified code:

• Indent: 2 spaces
• Quotes: Keep as-is
• Semicolons: Keep as-is
• Just make it readable!

Standardizing legacy code:

• Indent: 2 spaces (modern standard)
• Quotes: Single (most popular)
• Semicolons: Add missing (safe)
• Trailing comma: ES5

Learning from examples:

• Indent: 2 spaces (easy to read)
• Quotes: Keep as-is (preserve original)
• Semicolons: Keep as-is
• Focus on structure

Preparing for production:

• Use Prettier or ESLint instead
• Or: 2 spaces, single quotes, add semicolons
• Then: Minify for production

Keyboard Shortcuts

Browser shortcuts (if supported):

• Ctrl/Cmd + V: Paste code
• Ctrl/Cmd + A: Select all
• Ctrl/Cmd + C: Copy

Workflow:

1. Paste code (Ctrl+V in input)
2. Click "Beautify Code"
3. Click "Copy Output"
4. Paste in your editor (Ctrl+V)

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Note: For production projects with teams, we strongly recommend using Prettier or ESLint with autofix for consistent, automated code formatting. This tool is perfect for quick formatting, debugging minified code, and learning.