TypeScript Quiz

Pass with 7 / 10 to unlock your certificate.

1. 1. What does the `unknown` type require before use?

   NothingA type assertion or narrowingAn importA cast to any

2. 2. Which utility type makes all properties optional?

   Required<T>Partial<T>Readonly<T>Pick<T,K>

3. 3. What does a tuple type `[string, number]` represent?

   Either a string or numberA fixed-length array with specified typesAn object with two keysAn enum

4. 4. What is structural typing?

   Types match by nameTypes match by shapeTypes are runtime checkedTypes are dynamically inferred

5. 5. Which operator narrows a union by checking a property?

   typeofinstanceofinAll of the above

6. 6. What's the difference between `interface` and `type`?

   No differenceInterfaces can be merged, types cannotTypes can't be extendedInterfaces can't describe functions

7. 7. What does `as const` do?

   Marks a variable as constInfers the narrowest readonly literal typeCompiles to a constantRemoves types

8. 8. Which is a generic constraint?

   <T extends string><T : string><T = string><T is string>

9. 9. What does `never` represent?

   A nullable valueA value that never occursAn empty objectThe any type

10. 10. Which flag enables strict null checks?

    --strict--noImplicitAny--strictNullChecks--checkAll