A structured lesson workspace with readable content, hands-on examples, and a clean path to completion.
| Observation | Diagnostic question |
|---|---|
| Runtime value | What value actually arrived? |
| Language rule | Which rule determines the result? |
const result = Promise.resolve(21).then(value => value * 2).catch(error => console.error(error));result.then(console.log);
This example demonstrates building real-world asynchronous applications directly. Change one input at a time and observe the result; the goal is to connect the syntax to the runtime behavior rather than treating the snippet as a recipe.
This example demonstrates building real-world asynchronous applications directly. Change one input at a time and observe the result; the goal is to connect the syntax to the runtime behavior rather than treating the snippet as a recipe.
The common trap is to memorize syntax while missing the boundary around it. Watch the inputs, the resulting value, and the point where the browser or Node.js host takes over.
Finish the lesson once you have worked through the material. This awards ★ 20 XP.