Input
Developer utility
JavaScript Formatter
Beautify, conservatively minify and inspect JavaScript without uploading or executing it. Preserve strings, nested templates, regular expressions, comments and line breaks that affect automatic semicolon insertion.
Source size
Lines
Tokens
Functions
Output
Formatted or minified JavaScript
Validation hints
Syntax and structure checks
Code outline
Detected JavaScript structure
| # | Type | Name | Line | Signature |
|---|
Examples
JavaScript samples
JavaScript formatting quick reference
| Construct | Example | Formatting behavior |
|---|---|---|
| Block | if (ready) { run(); } | Braces create an indented block. |
| Function | function sum(a, b) {} | Parameters stay together and the body expands. |
| Arrow function | items.map(x => x.id) | The arrow operator receives readable spacing. |
| Template literal | `Hello ${name}` | Nested template contents are preserved as protected tokens. |
| Regular expression | /^[a-z]+$/i | Regex bodies, escapes and character classes are preserved. |
| Comment | // note | Comments can be retained or removed; shebang lines are always preserved. |
Formatting and safety notes
ASI-safe line handlingOriginal line breaks are preserved so return, break, continue, postfix operators and semicolon-free statements do not change meaning.
Protected syntaxStrings, Unicode identifiers, nested template literals, regular expressions, comments and shebang lines are tokenized before spacing changes.
Never executedOrdinary scripts may be compiled for syntax checking with Function, but pasted code is never called or run.
Practical formatterThis browser tool is not a replacement for a project-aware parser, Prettier, ESLint or a production bundler. Review output before deployment.
JavaScript formatter FAQ
Does this JavaScript formatter upload my code?
No. Formatting, tokenization, statistics and checks all run locally in the current browser tab.
Does the tool execute pasted JavaScript?
No. It may compile ordinary script source to detect syntax errors, but it never calls the resulting function or executes the program.
Can it handle ES modules and modern syntax?
It preserves imports, exports, classes, optional chaining, Unicode identifiers, regex literals and nested templates. Module checks are structural because the browser API does not expose a no-execution module parser.
Why does minified output keep line breaks?
Some JavaScript line breaks affect automatic semicolon insertion. Keeping them is a conservative choice that avoids changing semicolon-free code.