Your first lesson is a short, hands-on coding activity inside the browser. You do not need to install anything.
What you will see
When you open a lesson, the screen is split into a few areas:
- Instructions on the left: what you need to build or fix.
- Editor in the center: a Monaco code editor where you write or edit code.
- Run button above the editor: runs your code and checks it against tests.
- Console / Preview tabs below the editor: read test output or see a live preview.
A typical flow
- Read the instructions carefully.
- Look at the starter code in the editor.
- Make the requested change.
- Press Run.
- Check the console for test results. If a test fails, read the message — it usually points to the exact line.
- Press Hint if you are stuck, or peek at a solution hint when one is available.
- When all tests pass, click Next to continue.
Example
A JavaScript lesson might show:
function double(x) {
// your code here
}
// tests
console.assert(double(2) === 4)
console.assert(double(5) === 10)
If you type return x * 2; and press Run, the tests pass and your progress is recorded.
What happens behind the scenes
Pure JavaScript and TypeScript run in an in-browser iframe sandbox. HTML/CSS/JS lessons render a live preview. Node.js and backend lessons run in WebContainer, a browser-based Node.js runtime.
Next steps
- Try a lesson from the Dashboard.
- Learn about content types in Content types & difficulty levels.
- Read Practice problems to understand feedback.