JavaScript Beautifier & Formatter
Format, beautify, and organize your JavaScript, JSX, and TSX code instantly. Supports indentation control, semicolons, quote style, and more.
What is JavaScript Beautification?
JavaScript beautification is the process of reformatting JavaScript source code so that it follows a consistent, readable style without changing what the code does. Minified bundles, copy-pasted snippets, and generated files all tend to arrive as a single dense run of characters. A beautifier turns that back into well-indented, line-broken code that a human can read, review, and debug.
This tool wraps the widely used js-beautify library in a simple browser interface. The library understands JavaScript syntax well enough to indent blocks, align chained calls, and space operators correctly, and it also recognizes JSX and TSX so that component markup in React and TypeScript React files is handled properly. A minify mode is included as well, which collapses the code back down for production use.
Formatting is not just cosmetic. Consistent indentation makes control flow easier to follow, highlights mismatched braces, and reduces the chance that a reviewer misses a subtle bug. Standardizing semicolons and quotes across files also prevents noisy diffs when several developers work in the same repository, because small stylistic changes no longer show up as unrelated edits.
The beautifier runs entirely in your browser with no server round trip, so your source code never leaves your machine. If the input cannot be parsed, a clear error banner explains the problem instead of failing silently, which makes the tool useful for a quick syntax sanity check as well as for formatting.
Key Concepts
- Beautify — adds indentation and line breaks to make code readable.
- Minify — removes whitespace and comments to shrink the output.
- Indentation — choose 2 spaces, 4 spaces, or tab characters.
- Semicolons — preserve existing ones, always add them, or remove them.
- Quote style — preserve, or normalize strings to single or double quotes.
- JSX and TSX — component markup and TypeScript syntax are understood.
How to Use
- Paste your code — Copy and paste any JavaScript, JSX, or TSX code into the top textarea. You can also type directly or use the Example link to load sample code.
- Choose options — Select indentation style (2 spaces, 4 spaces, or Tab), semicolon behavior (Preserve, Always add, or Remove), and quote style (Preserve, Single, or Double).
- Format or Minify — Click Format JS to beautify with proper indentation, or Minify to compress into a compact form.
- Resolve any error — If the code cannot be parsed, an error banner appears with a message you can use to fix the input.
- Copy or download — Use the copy button on the output area or click Download .js to save the result.
Options Reference
The formatter exposes three option groups. Each setting is applied when you click Format JS or Minify.
| Option | Values | Effect |
|---|---|---|
| Indent | 2 / 4 / tab | Sets the number of spaces or uses a tab character for each level of nesting. |
| Semicolons | preserve / add / remove | Keeps existing semicolons, adds missing ones, or strips them in ASI style. |
| Quotes | preserve / single / double | Leaves strings as written or converts them to single or double quotes. |
| Max preserved newlines | 10 | Caps runs of blank lines during beautification to keep output compact. |
| End with newline | on / off | Adds a trailing newline when formatting; off when minifying. |
Minify ignores the indent and newline options and additionally removes block comments and collapses whitespace around punctuation.
Worked Examples
- Compact function —
function f(){return 1;}becomes a multi-line function with an indented return statement. - Chained calls — a long
items.filter().map().reduce()chain is broken across lines while each method stays on its own line. - Add semicolons —
const a = 1becomesconst a = 1;when the semicolon mode is set to Always add. - Remove semicolons — trailing semicolons before a closing brace are dropped when the mode is set to Remove.
- Normalize quotes — a double-quoted string becomes single-quoted when the quote mode is set to Single.
- Minify — a formatted file with comments is compressed onto one line with block comments removed.
Tips and Common Mistakes
- Format before you debug — beautifying minified code first makes stack traces and line numbers far easier to follow.
- Beautifying is not validating — reformatting does not prove the code is correct; keep the error banner in mind as only a syntax guide.
- Quote conversion can break code — converting quotes inside strings that contain the other quote character may need manual review.
- Removing semicolons is risky — ASI rules can change behavior in rare cases, so only remove semicolons when you know the codebase is safe.
- Minify last — minify a final, tested file rather than editing minified output by hand.
- Check JSX blocks — nested JSX is indented clearly, but very complex conditional markup is still worth a quick manual read.
Common Use Cases
Formatting comes up whenever JavaScript is read by a person rather than a machine. These are the situations where this tool helps most.
- Reading minified code — expand a compressed file to inspect logic or trace a bug.
- Standardizing team style — apply the same indent, semicolon, and quote settings across files for clean diffs.
- Reviewing a snippet — paste code from a chat or issue and reformat it before reviewing.
- Preparing production bundles — use Minify to shrink a tested script for deployment.
- Learning and teaching — clear indentation makes examples easier to explain and understand.
- Cleaning generated output — reformat code produced by a build step or code generator.
Frequently Asked Questions
Does this tool support JSX and TSX?
Yes. The beautifier handles JSX (React) and TSX (TypeScript React) syntax correctly, preserving component tag structures and expression brackets.
Is my JavaScript data stored on a server?
No. All processing happens entirely in your browser using JavaScript. Your code never leaves your device.
What's the difference between semicolon options?
Preserve keeps your existing semicolons as-is. Always add ensures every statement ends with a semicolon. Remove strips unnecessary semicolons (ASI style).
Does this tool handle TypeScript?
Yes. The beautifier works well with TypeScript syntax including type annotations, interfaces, generics, and enums. For best results with complex TypeScript projects, consider using a dedicated TypeScript formatter.
Does beautifying change how my code runs?
No. Beautifying only changes indentation, line breaks, semicolons, and quote style. It does not alter the logic of the code.
What does Minify do?
Minify removes indentation and block comments and collapses whitespace around punctuation, producing a compact single-line output suitable for production.
Which beautifier library is used?
The tool uses the bundled js-beautify library, loaded on demand, and applies your chosen options on top of it.
Why do I see an error banner?
The error banner appears when the input cannot be parsed as JavaScript, for example because of a missing bracket or quote. It reports the problem so you can correct the source code.