JavaScript TypeScript Basics 3

Question 1

What does the TypeScript `never` type represent?

Accepted Answer

A type that has no values — used for functions that never return

Answer

`never` represents the type of values that never occur, such as a function that always throws or has an infinite loop.

Question 2

What is structural typing in TypeScript?

Accepted Answer

Type compatibility is based on the shape (structure) of the type, not its name

Answer

TypeScript uses structural typing, meaning two types are compatible if they have the same shape, regardless of their names.

Question 3

How do you make a function parameter optional in TypeScript?

Accepted Answer

Use a `?` after the parameter name

Answer

Adding `?` after a parameter name makes it optional, so callers may omit it.

Question 4

What is the difference between `interface` and `type` in TypeScript for defining object shapes?

Accepted Answer

Type aliases can use union and intersection types; interfaces cannot

Answer

While both can define object shapes, `type` aliases support unions, intersections, and mapped types, giving them more expressive power.

Question 5

Which compiler option enforces strict null checks in TypeScript?

Accepted Answer

strictNullChecks

Answer

The `strictNullChecks` option makes `null` and `undefined` distinct types, preventing accidental null reference errors.

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