JavaScript Syntax Validator
Check JavaScript code for syntax mistakes and errors online.
Unlike a full code linter, this JavaScript validator focuses on syntax errors rather than code style and formatting.
If an error is found, move the mouse over the squiggly red line to see the parser message and error location.
Your code is checked in your browser. JSValidator does not need to upload pasted code to validate its syntax.
Online JavaScript Validator and JS Syntax Checker
JSValidator is a fast JavaScript syntax checker for developers who want to validate JS code before running or publishing it. Paste JavaScript into the editor and the validator checks the source for parse errors, then highlights the location so you can fix the problem quickly.
Use it as a JavaScript checker, JS validator, syntax error checker, or lightweight JavaScript linter when your goal is to find invalid syntax. It is especially useful for missing brackets, malformed expressions, invalid declarations, unexpected tokens, and other errors that prevent JavaScript from being parsed.
How to validate JavaScript online
- Paste or type your JavaScript code in the editor.
- The validator checks the code automatically as you type.
- Review the status message and any red error marker.
- Fix the reported syntax error and validate again instantly.
What this JavaScript checker can detect
- Unexpected or invalid JavaScript tokens.
- Missing or unbalanced brackets, braces, and parentheses.
- Malformed function, variable, object, array, or expression syntax.
- Invalid statements and many common JavaScript parse errors.
JavaScript validator vs. JavaScript linter
A syntax validator answers one main question: can the JavaScript source be parsed correctly? A full linter such as ESLint can also enforce coding rules, flag style problems, identify some suspicious patterns, and apply project-specific configuration. JSValidator intentionally stays focused on quick syntax validation.
JavaScript Validator FAQ
What is a JavaScript validator?
A JavaScript validator checks source code for syntax that a JavaScript parser cannot understand and reports the location of the error.
Does JSValidator execute my code?
No. The page parses the source to check syntax; it does not intentionally run the JavaScript you paste into the editor.
Is this the same as ESLint?
No. JSValidator is primarily a syntax checker. ESLint is a configurable linter that can also enforce style and code-quality rules.
Can I use this as a JS syntax checker online?
Yes. Paste your code into the editor and validation updates automatically, making it useful for quick JavaScript syntax checks in the browser.