JS Validator

Validate JavaScript, JSX, TypeScript, and TSX snippets with syntax errors and lint-style warnings.

Code Input

Validation Result

No syntax errors detected

6 lines, 120 characters, 0 warnings

Issues will appear here.

Compiled Output

function greet(user) {
    const name = user?.name ?? "developer";
    return name.toUpperCase();
}
greet({ name: "Ada" });

JavaScript Validator

Validate JavaScript, JSX, TypeScript, or TSX syntax in the browser and catch common code quality warnings before pasting snippets into a project.

Checks included

Syntax diagnostics from the TypeScript compiler
Warnings for var, loose equality, eval, debugger, and console calls
Compiled JavaScript preview for TypeScript and JSX snippets

How to use JS Validator

The JavaScript validator checks JavaScript, JSX, TypeScript, and TSX snippets for syntax problems. It is useful before pasting code into a project or issue.

Developers often use this page when they need javascript checker, js validator, js checker, and javascript validator.

Privacy and data handling

This tool is designed to run in your browser for normal use, so your input does not need to be sent to a server.

Input and output stay on the page while you work.
Copy buttons use your browser clipboard permission when available.
Avoid pasting private production data on shared or untrusted devices.

Examples

Find a missing brace

Input

function hello() { console.log('hi');

Output

Syntax error: unexpected end of input

Syntax validation is a fast first check before running a snippet.

Steps

1Paste a code snippet into the editor.
2Choose the language mode if needed.
3Review validation output and fix the highlighted problem.

Common use cases

Check a snippet from docs or a ticket.
Validate small JSX or TSX examples.
Find syntax mistakes before running code.

Practical tips

Syntax validation does not catch every runtime bug.
TypeScript type errors may depend on your project config.
Run final code in your real project before shipping it.

FAQ

Can this validate TypeScript?

Yes, it can check TypeScript-style snippets, but full type checking may depend on your project settings.

Does validation run the code?

No. It checks syntax and parsing. It does not execute the code.