Code Editor

Console Output

Click "Run Code" to see output here...

Tips

Use console.log() to output values
All standard JavaScript features are supported
Code runs in a sandboxed environment
Press Ctrl+Enter or click "Run Code" to execute

What is JavaScript Console?

Need to test JavaScript code quickly without setting up a project? JavaScript Console is an interactive online playground where you can write and run JavaScript code instantly. Perfect for testing snippets, learning JavaScript, or debugging code on the fly.

The Console API is the first debugging tool most of us reach for, and this page gives you one without opening DevTools. Modern syntax works: arrow functions, classes, destructuring, template literals, async functions and promises. Logs from setTimeout callbacks and resolved promises show up too, even after the main code has finished.

Your code runs in your own browser, not on our servers. Each run gets a fresh, locked-down frame that is cut off from this site, so a snippet can't read your cookies or storage, and network calls like fetch are blocked. One thing to watch: an endless loop (while (true) {}) will still freeze the tab, just like it would in DevTools.

How to Use the JavaScript Console

Follow these steps to run and test JavaScript. Each step uses the actual buttons and panels on this page.

Write Code or Load Sample

Type JavaScript in the editor, or click Sample to load example telecomm subscriber code. Use console.log() to output values. Example:

const subscriber = { subscriberId: "SUB-1001", plan: "Unlimited 5G", dataUsage: 45.2, status: "active", carrier: "Verizon" };
console.log("Subscriber:", subscriber);

Run Your Code

Click Run Code or press Ctrl+Enter to execute. Code runs in a sandboxed environment. Output appears in the console panel below.

View Output

See output from console.log(), console.error(), and other console methods. Click Clear to start fresh. All execution runs in your browser.

When You'd Actually Use This

Learning JavaScript

Learn JavaScript by testing code snippets. Experiment with different syntax and see results instantly. Perfect for beginners and experienced developers.

Quick Testing

Test JavaScript code snippets quickly without creating a full project. Perfect for debugging or verifying code logic before adding to your project.

Prototyping

Prototype JavaScript ideas quickly. Test algorithms, data structures, or API calls without setting up a development environment.

Code Examples

Share JavaScript code examples with others. Run code to demonstrate concepts or show how something works.

Common Questions

Is my code stored?

No. The code runs in your browser and is never sent to our servers. We don't save it anywhere, so copy anything you want to keep before you close the tab.

What JavaScript features are supported?

Plain modern JavaScript, the same as your browser supports: ES2015+ syntax, classes, arrow functions, promises and async functions. One limit: top-level await isn't supported, so wrap it in an async function, e.g. (async () => { ... })(). The full language is defined in the ECMAScript specification.

Can I use external libraries?

No. There's no import, require or script loading, and network requests are blocked, so packages from npm won't load. It's for testing plain JavaScript and the built-in browser APIs. For Node-specific code, run it with Node.js locally.

Is it safe to run code?

Your code runs in a sandboxed frame with no access to this site, your cookies or local storage, and network requests are blocked. It can't touch your files either. The one thing it can still do is hang the tab with an endless loop; if that happens, reload the page.

How do I see output?

Use console.log() to output values. All console methods (console.log, console.error, console.warn, etc.) work and display in the output panel.

Can I clear the output?

Yes! Click "Clear Output" to clear the console output. Perfect for running multiple tests without old output cluttering the view.

Other JavaScript Tools You Might Need

Testing is just one JavaScript task. Here are other tools that work well together: