What is JavaScript syntax formatting?

JavaScript formatting is the process of checking whether source code is valid and then reflowing it into a consistent style. That usually means adjusting indentation, spacing, and line breaks without changing the meaning of the code.

Syntax validation is just as important. A formatter can only safely rewrite code if the parser can understand it first.

Tool description

This tool validates JavaScript syntax and formats the code in the browser. It uses a parser to check whether the input is valid and Prettier to produce a cleaner version of the same source.

It is useful when you want a quick formatting pass or a syntax check without opening a full IDE.

Examples

  • A small ES module with imports and exports
  • A JSX snippet such as a React component
  • A long object literal that needs indentation cleanup

Features

  • Syntax validation with Babel parser
  • Formatting with Prettier standalone
  • Clear-button workflow for fast resets

Limitations

This tool is syntax-only. It does not execute code and it does not support TypeScript input.

Empty input is rejected for both validation and formatting, so you need to provide actual code before using either action.