TypeScript Interview Questions and Answers

Question 1

What is TypeScript? What are the advantages of TypeScript over JavaScript?

Accepted Answer

TypeScript is an open-source programming language and a strongly typed superset of JavaScript.

Question 2

How to install TypeScript and check version?

Accepted Answer

Install TypeScript with npm, then verify the installed compiler with the `tsc --version` command.

Question 3

What is the difference between let and var keyword?

Accepted Answer

`var` and `let` are both used for variable declaration, but `var` is function scoped while `let` is block scoped.

Question 4

What is Type annotation in TypeScript?

Accepted Answer

Type annotation means assigning a type to a variable, parameter, return value, or property so the compiler can check it.

Question 5

What are Built in/ Primitive and User-Defined/ Non-primitive Types in TypeScript?

Accepted Answer

Built-in or primitive types store simple data, while user-defined or non-primitive types store more complex structured data.

Question 6

What is "any" type in TypeScript?

Accepted Answer

When a value is of type `any`, the compiler performs no meaningful type checking for that value and you can assign anything to it.

Question 7

What is Enum type in TypeScript?

Accepted Answer

Enums allow us to define a set of named constants.

Question 8

What is the difference between void and never types in TypeScript?

Accepted Answer

`void` means a function returns nothing useful, while `never` means a function never completes normally.