JavaScript Formatter

Free online utility. 100% client-side processing with no signup required.

Free & instant 100% client-side No signup needed

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How to Use

  1. Paste your JavaScript code in the textarea
  2. Click "Format JavaScript" to beautify and add proper indentation
  3. Or click "Minify JavaScript" to compress code for production
  4. Click "Copy" to copy the formatted/minified code
  5. Use the code in your project or for debugging

{user.name}

{user.active?'Active':'Inactive'}

Features

Why Format JavaScript?

Formatted JavaScript is easier to read, debug, and maintain. When working with minified libraries or production code, formatting makes it possible to understand the logic, set breakpoints, and identify issues quickly.

Common Use Cases

Format vs Minify

Formatting (Beautify)

Adds proper indentation, line breaks, and spacing to make code readable. Use during development, debugging, and code review. Increases file size but improves maintainability.

Minification

Removes whitespace, line breaks, and comments to reduce file size. Use for production deployment to improve page load speed. Reduces file size by 30-60% but makes code unreadable.

JavaScript Formatting Standards

Modern JavaScript follows ESLint and Prettier standards for consistent code formatting. Our formatter applies industry-standard rules including 2-space indentation, semicolon usage, single quotes for strings, and proper spacing around operators. Consistent formatting improves code review efficiency and reduces merge conflicts.

ES6+ Modern JavaScript Features

  • Arrow Functions: Concise syntax with lexical this binding: const add = (a, b) => a + b
  • Destructuring: Extract values from objects and arrays: const {name, age} = user
  • Template Literals: String interpolation with backticks: \Hello \\
  • Async/Await: Cleaner asynchronous code than promises: async function fetchData() { await api.get() }
  • Spread Operator: Array and object manipulation: const newArray = [...oldArray, newItem]
  • Optional Chaining: Safe property access: user?.address?.city

JavaScript Best Practices

Use const by default, let when reassignment is needed, avoid var. Prefer arrow functions for callbacks and methods. Use strict equality (===) instead of loose equality (==). Handle errors with try/catch blocks. Avoid global variables and use modules for code organization. Comment complex logic but let code be self-documenting.

JavaScript Performance Optimization

Minimize DOM manipulation by batching updates. Use event delegation instead of multiple event listeners. Debounce and throttle expensive operations like scroll and resize handlers. Lazy load modules with dynamic imports. Use Web Workers for CPU-intensive tasks. Profile with Chrome DevTools to identify bottlenecks.

Common JavaScript Patterns

Module Pattern encapsulates private variables and methods. Observer Pattern for event-driven architecture. Factory Pattern for object creation. Singleton Pattern for single instances. Promise Pattern for asynchronous operations. Our formatter preserves these patterns while ensuring consistent code style.

JavaScript Frameworks and Libraries

React, Vue, and Angular dominate modern web development. React uses JSX syntax mixing HTML and JavaScript. Vue uses single-file components with template, script, and style sections. Angular uses TypeScript with decorators and dependency injection. Our formatter works with all frameworks while maintaining their specific syntax requirements.

TypeScript Integration

TypeScript adds static typing to JavaScript, catching errors at compile time. Use interfaces for object shapes, types for unions and intersections, and generics for reusable components. TypeScript improves IDE autocomplete and refactoring. Our formatter handles both JavaScript and TypeScript syntax including type annotations.

{user.email}

{user.role}

)} Output (formatted): function UserCard({ user, onEdit, onDelete }) { return ( <div className="card"> <div className="card-header"> <h2>{user.name}</h2> <span className={`badge ${user.active ? 'active' : 'inactive'}`}> {user.active ? 'Active' : 'Inactive'} </span> </div> <div className="card-body"> <p>{user.email}</p> <p>{user.role}</p> </div> <div className="card-footer"> <button onClick={() => onEdit(user.id)}>Edit</button> <button onClick={() => onDelete(user.id)} className="danger"> Delete </button> </div> </div> ); }

Common Use Cases

Paste your JavaScript and get clean, formatted output instantly. All formatting happens in your browser — your code is never sent to any server.

Examples

Example 1: Minified JavaScript → Formatted

Input (minified):
function fetchUser(id){return fetch('/api/users/'+id).then(r=>r.json()).then(data=>{if(!data.active){throw new Error('User inactive')}return data}).catch(err=>{console.error('Failed:',err);throw err})}

Output (formatted, 2-space indent):
function fetchUser(id) {
  return fetch('/api/users/' + id)
    .then(r => r.json())
    .then(data => {
      if (!data.active) {
        throw new Error('User inactive');
      }
      return data;
    })
    .catch(err => {
      console.error('Failed:', err);
      throw err;
    });
}

Example 2: ES6+ Modern JavaScript Formatting

Input (poorly formatted):
const {name,age,email}=user;const greeting=`Hello ${name}, you are ${age} years old`;const isAdult=age>=18;const processUser=async(userId)=>{const user=await getUser(userId);const{data:{profile:{avatar,bio}={}}={}}=user;return{...user,avatar:avatar||'default.png',bio:bio||'No bio provided'}};

Output (formatted):
const { name, age, email } = user;
const greeting = `Hello ${name}, you are ${age} years old`;
const isAdult = age >= 18;

const processUser = async (userId) => {
  const user = await getUser(userId);
  const {
    data: {
      profile: { avatar, bio } = {}
    } = {}
  } = user;

  return {
    ...user,
    avatar: avatar || 'default.png',
    bio: bio || 'No bio provided'
  };
};

Example 3: React JSX Formatting

Input (messy JSX):
function UserCard({user,onEdit,onDelete}){return(

Frequently Asked Questions

Yes, our Javascript Formatter is completely free with no registration required. Use it unlimited times without any restrictions.

Yes, all processing happens locally in your browser. Your data never leaves your device and is not stored on our servers.

No installation needed. The tool works directly in your web browser on any device.

No, formatting only changes the visual presentation. Your actual data remains unchanged.

Yes, use the available options to adjust indentation, spacing, and other formatting preferences.