JavaScript Validator

How this JavaScript checker works

The validator parses your code with Acorn, the same standards-compliant parser used by popular tools such as webpack and ESLint. It understands the latest ECMAScript syntax, including arrow functions, classes, async/await, optional chaining, private fields and top-level await in modules.

Your code is only parsed, never run, so it is safe to check any snippet.

Typical JavaScript syntax errors

• Missing closing bracket }, parenthesis ) or square bracket ]
• Unterminated string or template literal
• Using import/export without selecting “ES Module”
• Reserved words used as variable names (e.g. let class = 1)
• Using await outside an async function in a regular script

Does it check for logic errors?

No — this is a syntax validator. Code can be syntactically valid and still contain bugs, so test it in your environment as well.