Formatted JS will appear here...
Beautify JavaScript code with proper indentation and formatting. For complex JS files, consider using a professional formatter like Prettier.
What is JavaScript Formatter?
JavaScript formatters reorganize source code with consistent indentation, spacing around operators, and clear block structure. In practice, developers encounter minified JavaScript — code compressed into a single line with all whitespace removed for faster page loading — when debugging production issues, analyzing third-party scripts, or reviewing bundled output. Without formatting, minified code is virtually unreadable: variables blend together, function boundaries disappear, and control flow becomes impossible to trace. This tool reverses that compression by detecting brace-delimited blocks, adding proper line breaks after semicolons, and indenting nested structures like functions, conditionals, and loops. While it handles common JavaScript patterns including objects, arrays, and basic control flow, it uses pattern-based formatting rather than full AST parsing, so extremely complex syntax like chained ternary expressions or deeply nested arrow functions may benefit from a dedicated tool like Prettier for production use.
How to Use
- Paste JavaScript code (minified or unformatted)
- Select indentation preference (2 or 4 spaces)
- Click 'Format JS' to beautify the code
- Copy formatted output for your project
Why Use This Tool?
Tips & Best Practices
- 2 spaces is JavaScript convention
- Minified code needs formatting before editing
- Format before debugging - structure reveals bugs
- Use Prettier for production projects
- Check bracket balance after formatting
- Preserves comments in the code
Frequently Asked Questions
What does this formatter handle?
Basic JavaScript formatting: braces indentation, statement separation, operator spacing. Handles functions, objects, arrays, and basic control flow. Complex syntax (decorators, JSX, TypeScript) may not format perfectly - use Prettier for full formatting.
Should I use 2 or 4 space indentation?
2 spaces is JavaScript/TypeScript convention. 4 spaces works for teams that prefer more visible indentation. Match your project's existing style. Consistency matters more than the specific number.
What about semicolons?
This formatter preserves your semicolon usage - adding semicolons if present, respecting ASI (automatic semicolon insertion) if omitted. It doesn't enforce semicolon style. Use ESLint for semicolon rules.
Can formatting change code behavior?
No - formatting only changes whitespace, never logic. Indentation, spacing, and newlines don't affect JavaScript execution. Your code runs exactly the same before and after formatting.
What's the difference from Prettier?
This is a basic formatter for quick cleanup. Prettier is a professional formatter with full AST parsing, handling complex syntax, JSX, TypeScript, and supporting many configuration options. Use Prettier for production projects.
How do I format entire files?
Paste the full file content, format, and copy the result. For large files or multiple files, use Prettier CLI: prettier --write "src/**/*.js". This tool works best for individual snippets and quick formatting needs.
Is my JavaScript code kept private?
Yes. All formatting happens locally in your browser. Your code is never sent to any server, never stored, and never logged. The tool works entirely offline once the page has loaded.
When should I NOT use this formatter?
Avoid using this for TypeScript files with type annotations, JSX/TSX React components, or code using experimental syntax proposals — the pattern-based parser may misindent these. Also skip it for files that already use a consistent formatting standard managed by Prettier or ESLint in your project, since reformatting outside your build pipeline can create noisy diffs.
Real-world Examples
Reading a minified third-party library snippet
When debugging an issue with a bundled dependency, you need to read the minified output. Format it first to understand the logic.
function debounce(fn,delay){let timer;return function(...args){clearTimeout(timer);timer=setTimeout(()=>fn.apply(this,args),delay);};}function debounce(fn, delay) {
let timer;
return function(...args) {
clearTimeout(timer);
timer = setTimeout(() => fn.apply(this, args), delay);
};
}Cleaning up quickly-written code before review
Code written in a rush often has inconsistent indentation and missing line breaks. Format it before sharing for code review.
const fetchUser=async(id)=>{const res=await fetch(`/api/users/${id}`);const data=await res.json();if(!res.ok)throw new Error(data.message);return data;};const fetchUser = async (id) => {
const res = await fetch(`/api/users/${id}`);
const data = await res.json();
if (!res.ok)
throw new Error(data.message);
return data;
};