What is a JavaScript Formatter?
A JavaScript Formatter re-indents and restructures JS code to make it easier to read and maintain. This tool formats and minifies JavaScript entirely in your browser — your code is never sent to any server.
How to Use
- Paste your JavaScript into the input box on the left
- Click Format JS to beautify, or Minify to compress
- Click Copy to copy the output, or Download to save as
.jsor.min.js
The syntax checker runs automatically as you type — a green indicator means structure is valid, red means there is a bracket or brace mismatch.
Format vs. Minify
| Mode | What it does | When to use |
|---|---|---|
| Format | Adds consistent indentation, splits at {, }, ; | Reading, editing, code review |
| Minify | Removes comments and whitespace, collapses to one line | Production builds, reducing bundle size |
What the Minifier Removes
- Single-line comments (
// …) - Block comments (
/* … */) - Excess whitespace and newlines
String contents are preserved exactly — characters that look like comments inside strings are never stripped.
Indentation Options
Choose from 2 spaces (default), 4 spaces, or a tab character. The formatter respects the selected style for every indentation level.
Download
After formatting or minifying, click Download to save the result. Formatted code is saved as output.js; minified code as output.min.js.
Byte Savings
After minification, the tool shows how many bytes were saved and the percentage reduction compared to the original. Real transfer savings are even larger with gzip or Brotli compression on top.
Syntax Checking
The tool checks your JavaScript for basic structural errors in real-time:
- Unclosed braces — every
{must have a matching} - Unclosed parentheses — every
(must have a matching) - Unexpected closers — a
}or)without a matching opener is flagged
String literals and comments are excluded so characters inside them do not count.
Privacy
All processing runs locally in your browser using JavaScript. No code is ever uploaded, stored, or logged. You can use this tool offline once the page has loaded.