TypeScript in Depth · Final Project · Lesson 16 of 16
Building with Confidence
Concept
Building with Confidence
With interfaces and generics in place, TypeScript catches typos and mismatched types as you build, letting the compiler guide you.
By the end of this lesson
- Explain the core idea behind Building with Confidence.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
How to study this page
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
ExampleRunnable
function toggleTask(tasks: Task[], id: string): Task[] {
return tasks.map((t) => (t.id === id ? { ...t, done: !t.done } : t));
}Self-check before continuing
Without looking at the example, describe what changes when you modify one input in Building with Confidence. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Write a typed function that adds a new Task to an array of tasks.
Loading editor…
Console