# JavaScript & TypeScript Formatter

> Format JavaScript, TypeScript, JSX and TSX properly with Prettier.

To format JavaScript or TypeScript, paste your code and it is parsed into an abstract syntax tree by Prettier and reprinted with consistent style. Because it parses rather than pattern-matches, template literals, JSX and comments survive intact, and a syntax error is reported with its location.

**URL:** https://convertto.tech/t/javascript-formatter
**Category:** Data & Format Tools (https://convertto.tech/c/data-tools)
**Privacy:** Runs entirely in the browser; no upload
**Cost:** Free, no sign-up
**Last updated:** 2026-08-01

## Key facts

- **Engine:** Prettier, running in your browser
- **Correctness:** AST-based — output is always valid syntax
- **Privacy:** Runs entirely in your browser — nothing is uploaded
- **Cost:** Free, unlimited, no sign-up

## How to use

1. Enter or paste your code.
2. Choose the language.
3. Turn "Semicolons" on or off as needed.
4. Turn "Single quotes" on or off as needed.
5. Set the line width.
6. Set the indent size.
7. Turn "Indent with tabs" on or off as needed.
8. The result appears immediately — copy or download it.

## FAQ

### Why does the formatter reject my code?

Prettier must parse the code before it can print it, so genuinely invalid syntax fails rather than being silently mangled. The error shows the line where parsing stopped.

### Does formatting change what my code does?

No. Prettier only changes whitespace, quote style, semicolons and line breaks. The parsed program is identical — that is the guarantee an AST-based formatter provides over a regex one.

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