Online JavaScript Formatter

What is a JavaScript Formatter?

I built this JavaScript Formatter to rescue you from tangled one-line scripts and wild indentation. It is a browser-based utility that uses the popular js-beautify library to turn compacted or messy JavaScript into neatly indented, easy-to-read code. Everything runs locally in your browser, so your data stays private and you do not need to install anything.

What Does Our JavaScript Formatter Do?

When you paste your raw JavaScript into the input box and click Format JavaScript, the tool invokes js_beautify with sensible defaults: two-space indentation, spaces inside empty parentheses, and consistent line breaks. It parses your code, restructures blocks (if, for, function, etc.), aligns braces, and wraps long statements at sensible points. If the library encounters a syntax error it returns a clear comment indicating the problem, so you know exactly where to look.

What to Expect When Using This Tool

On page load you will see two panels labeled JavaScript Input and Formatted Output. On wide screens they sit side by side, on mobile they stack vertically. You paste your code on the left, click Format JavaScript, and instantly see the beautified version on the right. Hitting Clear All resets both fields so you can start fresh. The interface is minimal—just two textareas and two buttons—so you can focus completely on your code.

Common Use Cases

• Cleaning up minified code before review: When you pull in a JavaScript snippet that has been minified, this tool helps you expand it back into a readable form.
• Preparing code samples for blog posts or tutorials: No one enjoys reading a wall of unindented code. A quick format makes your examples clear and professional.
• Standardizing team style: If different team members use different editors or formatting rules, this tool provides a consistent baseline.
• Debugging nested logic: Deeply nested callbacks or promise chains become easier to trace once properly indented.
• Quick one-off formatting: You do not need a build pipeline or editor plugin—just paste and click.

Input and Output Examples

Example 1

Input:

function greet(name){console.log("Hello, "+name+"!");}

Output:

function greet(name) {
  console.log("Hello, " + name + "!");
}

Example 2

Input:

if(flag){doSomething()}else{doSomethingElse()}

Output:

if (flag) {
  doSomething();
} else {
  doSomethingElse();
}

Example 3

Input:

const add=(a,b)=>{return a+b;}

Output:

const add = (a, b) => {
  return a + b;
};

Frequently Asked Questions (FAQs)

What if my code has a syntax error?

The formatter will catch the parsing error and return a comment like // Error formatting code: Unexpected token …. You can then correct the syntax and retry.

Does it preserve comments and string content?

Yes. Inline and block comments remain intact, and string literals are never modified. Only whitespace and line breaks around tokens are adjusted.

Can I format ES6+ syntax (classes, async/await, import/export)?

Absolutely. The underlying js-beautify library supports modern JavaScript syntax. You will see classes, arrow functions, async/await, and spread operators formatted correctly.

Do I need an internet connection?

Yes, you need to load the js-beautify scripts from the CDN at first. After they are cached, you can even format offline.

How do I control indentation size?

The tool is preset to two spaces for readability. If you need a different style, you can modify the indent_size parameter in the formatJS function in the script.

Will it break my minified production code?

It will expand it for reading, but will not alter semantics. After formatting, you can copy the code back into your project or minify again for production.

Can I use this on mobile devices?

Yes. The layout adapts to small screens by stacking the textareas vertically. You can format code from your phone or tablet.

Does my code leave my browser?

No. All formatting runs in your browser’s JavaScript engine. Nothing is sent to any server.

Is this tool open source?

The UI wrapper is custom, but it uses the open-source js-beautify library (MIT license). You can inspect the library code in your browser’s developer tools.

Benefits of Using Formatted JavaScript

• Consistent, readable code for you and your team
• Faster debugging thanks to clear block structure
• Professional-looking code samples for documentation
• Zero setup—no editor plugins or build steps needed
• Privacy and speed: everything runs in your browser

Best Practices

• Keep unformatted originals for version control or reformatting
• Format before code reviews to focus on logic, not spacing
• Use clear, descriptive variable names alongside formatting
• Integrate formatting into your workflow by bookmarking this tool
• Avoid manual spacing tweaks—let the formatter ensure consistency

Getting Started

1. Open the JavaScript Formatter page in your browser.
2. Paste or type your raw JavaScript into the JavaScript Input textarea.
3. Click Format JavaScript.
4. Review the beautified code in the Formatted Output pane.
5. Copy the formatted code back into your editor or project.
6. Click Clear All to reset and format new code.

Give it a try now and see how quickly your code transforms from tangled to tidy!