Why format JavaScript?
Unformatted JavaScript is hard to follow: everything on one line, inconsistent indentation, a mix of quote styles. That happens with minified files, code pasted from a chat or a forum, or projects without a shared style. Formatting rewrites the code with consistent indentation, spacing and line breaks so the structure of functions, objects and conditions is visible at a glance.
This tool uses Prettier with the Babel parser, which understands modern JavaScript, JSX (React components) and JSON. You can set the indentation (2 spaces, 4 spaces or tabs), the line width (80, 100 or 120), whether statements end with semicolons, single or double quotes, and trailing commas in multi-line arrays, objects and parameters. These are the same options a Prettier config in a project would have, so you can match your codebase.
Formatting does not change what the code does. When you beautify a minified file, the structure becomes readable again, but local variable names that the minifier mangled to single letters stay that way: no tool can know what they were called. If the code has a syntax error, you see the parser message and its position.
The code is formatted in your browser and never uploaded. You get one free try per tool: one file or one pasted text. After that you can still re-process the same text with different options, but new input needs ToolStudio Pro, which gives unlimited use of every tool, several files at once downloaded together in a ZIP, and no ads. You can cancel anytime.
How to format JavaScript
- Paste your JavaScript, JSX or JSON, or drop a file.
- Choose indentation and line width.
- Set semicolons on or off, single or double quotes, and trailing commas.
- Run the formatter, fix any syntax error shown, then copy or download the result.
When a JavaScript formatter helps
- Reading a minified script to understand or debug it.
- Cleaning up code snippets from Stack Overflow, chats or AI answers.
- Pretty-printing a JSON response or config file.
- Formatting a React component written in JSX.
- Applying a consistent style before sharing code in a review or a tutorial.
Semicolons and trailing commas
Without semicolons, JavaScript inserts them automatically (ASI). Prettier knows the few cases where that is ambiguous, such as a line starting with ( or [, and adds a leading semicolon there, so turning semicolons off is safe. Trailing commas (for example [1, 2, 3,] written over several lines) make diffs cleaner, because adding an item changes one line instead of two.
Frequently Asked Questions
Can it unminify JavaScript?
It re-indents and re-structures the code so it is readable. Variable names that a minifier shortened cannot be restored.
Does it support JSX and JSON?
Yes. The Babel parser handles JavaScript, JSX and JSON.
Does it support TypeScript?
No, this formatter covers JavaScript, JSX and JSON.
Will formatting change how my code runs?
No. Prettier only changes formatting: whitespace, line breaks, quotes, semicolons and trailing commas, never the logic.
Is it free?
One file or one pasted text is free, and you can re-format it with other options. New input needs ToolStudio Pro, which gives unlimited use, several files at once in a ZIP and no ads.