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JavaScript Formatter — Beautify JS & TypeScript Code Online

JavaScript Formatter uses Prettier with Babel parsing to reformat JavaScript and TypeScript code. It applies consistent indentation, semicolons, and quote style.

What Prettier Fixes in Your JavaScript

Prettier is an opinionated code formatter that enforces a consistent style by reprinting code from scratch according to its rules. It normalises: indentation (2 spaces by default), semicolons (added), quote style (double quotes by default), trailing commas in multi-line expressions (where valid in ES5+), line length (80 characters, wrapping long expressions), and object/array brace spacing.

Prettier does not change your logic — it only changes whitespace and punctuation. A function that works before formatting works identically after. This makes it safe to apply to any JavaScript or TypeScript code without introducing bugs. The Babel parser used here supports the full ES2024 syntax plus TypeScript, JSX, and decorators.

Reading Minified JavaScript

Production JavaScript bundles are minified: variable names shortened to single letters, all whitespace removed, multiple statements collapsed onto one line. Formatting a minified bundle restores the whitespace and line breaks, making the code structure readable. The variable names remain shortened (renaming them is a separate deobfuscation step), but the control flow — if/else branches, loops, function calls — becomes clear.

This is useful when debugging a third-party script, understanding a bundled library, or auditing code for security. Paste the minified code, format it, then search for specific function names or string literals. For deeper analysis, follow the source map to the original unminified source if it is available.

Common Use Cases

  • Formatting minified JavaScript for readability
  • Standardizing code style before committing to version control
  • Beautifying TypeScript code snippets from documentation

Frequently Asked Questions

Does the JavaScript formatter support TypeScript?

Yes. SmartDevBox uses Prettier with the Babel parser, which supports modern JavaScript and TypeScript syntax including JSX, async/await, decorators, and optional chaining.

Privacy & Security

This tool runs entirely in your browser using client-side JavaScript. No data is sent to a server — your input never leaves your machine. SmartDevBox has no account system, no usage tracking, and no paid tier. See the Privacy & Security page for full details.

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