JavaScript Formatter
Inspect formatted or minified source without executing the script.
Runs in your browser. Nothing is uploaded.
Format JavaScript privately
JavaScript Formatter puts a readable layout around code while it stays in your browser. Paste a snippet, choose Format, and inspect the result in the second pane. Nothing is uploaded when you paste, format, copy, or download JavaScript. The page does not execute the code, import packages, call an API, or resolve files referenced by the code.
This browser-only workflow is useful when a log, ticket, minified bundle, or code review contains a small piece of JavaScript that needs a quick visual pass. It is also suitable for private snippets that should not be sent to an online formatting service. The output is text that you can compare with the input before you copy it elsewhere.
Formatter versus validator and linter
A formatter changes whitespace and line breaks to make code easier to read. It is not a validator, so a successful result does not prove that the program parses or runs. It is not a linter either, so it does not report unused variables, risky APIs, style violations, type errors, or framework rules. Use your project compiler, test suite, and linter when those checks matter.
Formatting can still be a helpful first step. A stable layout makes braces, comments, regular expressions, and statement boundaries easier to inspect. If the input is incomplete or unusual, read the result as a best-effort view rather than as a diagnosis of the underlying syntax.
What this JavaScript formatter does
The formatter uses a lightweight tokenizer. It recognizes quoted strings, template literals, comments, regular expression literals, operators, and punctuation before it applies indentation. That keeps braces inside a string, a template, or a regular expression from being mistaken for a code block. Blocks and object literals are opened on their own lines, statements ending in semicolons are separated, and comments remain in the output.
Format uses two spaces by default. The Indent control also offers four spaces and tabs. Minify collapses whitespace outside protected JavaScript tokens for a compact result. Comments are kept, including line comments, because removing comments can hide context or change the review result. Minification is a text transformation, not a bundler or compression pipeline.
Why it is not an AST or Prettier replacement
This is a lightweight JavaScript text formatter, not an AST formatter or Prettier replacement. Use a project-aware formatter for TypeScript, JSX, and framework-specific syntax.
Paste, sample, or drop a local file
Use Sample to load a short greeting function, paste your own source into JavaScript input, or choose a local .js, .mjs, or .cjs file. The file is read in the page before formatting. Format and Minify use the current input and mode. Copy places the current output on your clipboard, while Download saves formatted.js. Press Ctrl+Enter on Windows or Linux, or Cmd+Enter on macOS, to run the selected action from the input field.
Related local tools
CSS in the same browser-only workflow can be handled by the CSS Formatter. For markup, use the HTML Formatter. These tools are text formatters, so check the result in the context of your own build, parser, and deployment process.
FAQ
Can I format a local JavaScript file privately?
A dropped .js, .mjs, or .cjs file is read as text and formatted in your browser. The source is never uploaded, and TheDevTab never receives it.
Is this JavaScript Formatter a validator or linter?
No. It is a best-effort formatter and minifier, not a parser, linter, or security analyzer. It does not prove that code parses, runs, follows a style guide, or has no type or quality problems.
How are strings, templates, and regular expressions handled?
Quoted strings, template literals, and regular expression literals are scanned as protected tokens, including template expressions and regex character classes. Braces, semicolons, and comment markers inside those tokens are not treated as surrounding JavaScript structure.
Can I minify JavaScript?
Yes. Minify removes ignorable whitespace outside strings, comments, regular expressions, and template literals while preserving the spaces needed between tokens. Comments remain in the output, including line comments with their line break.
Which JavaScript files can I drop?
The file picker accepts .js, .mjs, and .cjs files. The Sample button loads a short greeting function so you can inspect the formatter without supplying a file.
Which JavaScript dialect does the formatter support?
It uses a lightweight tokenizer for common browser JavaScript. It is not a complete parser for TypeScript, JSX, Babel plugins, or framework-specific syntax, so use project-aware tooling for production changes.