JS Playground — JavaScript Runner Online Free
Need to run JavaScript code online? FlexyPdf's JavaScript Runner includes a powerful js playground capability that makes this easy. This page focuses specifically on the js playground functionality — how it works, when to use it, and tips for getting the best results. All processing happens in your browser for maximum speed and privacy. No software to install, no account to create.
How to Use JavaScript Runner
Write Your JavaScript Code
Type or paste JavaScript code into the Monaco editor. ES2022+ syntax is supported including async/await, optional chaining, nullish coalescing, and destructuring.
Click "Run JavaScript"
Press Run JavaScript. The code is sent to a Node.js 20 container, executed securely within 5 seconds, and all console.log() output is captured and returned.
Review Output
stdout appears in the green console panel. Uncaught exceptions and stack traces appear in red. Copy the code or run again immediately without page reload.
Features
Node.js 20 LTS Runtime
Full Node.js 20 LTS runtime with native ES modules, modern V8 engine, and all built-in Node.js core modules available.
ES2022+ Syntax Support
Write modern JavaScript with top-level await, class fields, logical assignment operators, and all ECMAScript 2022 features.
Monaco Code Editor
VSCode-grade editor with IntelliSense, JavaScript syntax highlighting, auto-closing brackets, and multi-cursor support.
Secure Execution
Runs in a Docker container with no network access, 128 MB memory limit, and automatic cleanup after every execution.
Benefits of Using JavaScript Runner
Completely Free
Use JavaScript Runner without any cost, limits, or hidden fees. No premium plans needed.
No Installation
Works directly in your browser. No software downloads or plugins required.
100% Private
Your files and data are processed locally. Nothing is uploaded to external servers.
Works Everywhere
Compatible with Chrome, Firefox, Safari, Edge on desktop, tablet, and mobile.
No Sign-Up
Start using the tool immediately. No account creation or email verification.
Always Available
Access this tool 24/7 from anywhere in the world, on any device.
Frequently Asked Questions
Complete Your Compiler Workflow
These free tools work seamlessly with JavaScript Runner to handle every step of your workflow.