JavaScript Validator
Check JavaScript syntax and pinpoint the exact error.
Processed locally in your browser. Nothing you enter is uploaded or stored.
- Parses with the same engine class of tool that build systems use — a real syntax check, not a guess.
- Points at the exact line and column of the first error.
- Runs in your browser; code isn't uploaded.
Why this is private
- Processed locally in your browser. Nothing you enter is uploaded or stored.
- Open your browser's DevTools → Network tab while using this tool — you won't see a request carrying your input, because it never leaves your device.
- Nothing you enter is uploaded to a server or shared with us — the processing happens entirely on your device.
Overview
Checks whether JavaScript is syntactically valid, using a real parser (not a linter's heuristics), and reports the exact line and column of the first syntax error.
How to use it
- 1Paste JavaScript code.
- 2Validation runs automatically as you type.
- 3If invalid, the exact error position and reason are shown.
Tips
- This checks syntax only — code that parses fine can still throw at runtime (a missing variable, a wrong argument count). For behavior bugs, run the code.
Frequently asked questions
What people use it for
Debug a build failurePaste the file a bundler is rejecting to find the exact unexpected token.
Check code pasted from a chat or forumConfirm a snippet is syntactically complete before dropping it into your project.
Verify generated or templated JSCheck output from a code generator or template engine actually parses.
Related guides
- How to read JSON with a tree viewerA tree viewer turns a wall of brackets into a structure you can expand, search and copy paths from. Here's how to use one effectively.
- JSON parse errors explained: 'Unexpected token', 'Expected comma or brace', and the restWhat each common JSON error message actually means, the usual cause, and how to find the spot fast using line and column.
- How to format JSON (and actually understand the errors)JSON looks like a JavaScript object but follows stricter rules. Here's what those rules are and how to read the errors when they're broken.
Related tools
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JavaScript Validator