Excellent Typescript Test - 87+ MCQs: TypeScript test: Evaluate Your Programming Skills with TypeScript Questions and Answers

1. What does the 'as' keyword do in TypeScript?

Type casting

Variable declaration

Function invocation

Type checking

2. How do you declare a readonly array in TypeScript?

let readonlyArray: ReadonlyArray<number>

let readonlyArray: number[] readonly

readonly let readonlyArray: number[]

let readonlyArray: const number[]

3. Which data type represents a collection of values in TypeScript?

Object

Array

Tuple

Enum

4. Which TypeScript feature is used for ensuring code blocks are never reached?

typeof

never type

undefined type

void type

5. What is the purpose of the 'interface' keyword in TypeScript?

To define a new class

To declare a function

To create a contract for object structure

To import external libraries

6. In TypeScript, which of the following is the correct way to define an array of numbers?

let numbers: number[];

let numbers: array<number>;

let numbers: Array[number];

let numbers: [number];

7. How do you define a class in TypeScript?

class MyClass {}

create class MyClass {}

new class MyClass {}

type MyClass {}

8. What is TypeScript's 'export' keyword used for?

To import a module

To define a class

To export a module or module member

To declare a variable

9. What is the purpose of the 'extends' keyword in TypeScript?

To create a new class

To declare a variable

To extend the functionality of a class

To define a function

10. What is the purpose of TypeScript's 'class' keyword?

To declare a new function

To create an instance of a class

To define a new data type

To define a blueprint for creating objects

11. What is TypeScript's equivalent of JavaScript's 'null'?

undefined

void

null

nil

12. In TypeScript, what is the difference between 'interface' and 'type' when defining a new type?

Interfaces are only for objects, while types can be used for primitives too

Types can be used for unions and intersections, interfaces cannot

Interfaces can be merged, but types cannot

All of the above

13. What does the 'is' keyword do in a TypeScript type predicate?

Checks if a type is assignable to another

Defines a custom type guard

Specifies an inheritance relationship

Creates a conditional type

14. In TypeScript, what is the purpose of the 'as' keyword?

To define a class

To cast one type into another

To create a loop

To print output

15. Which TypeScript keyword is used to indicate that a function doesn't return any value?

none

null

undefined

void

16. What is TypeScript's 'type alias' used for?

To define a class

To create a new object

To create a custom name for a data type

To print output

17. In TypeScript, how do you define an optional function parameter?

By using 'optional' keyword

By using 'required' keyword

By using a question mark '?'

By using a colon ':'

18. In TypeScript, what is the purpose of the 'import' statement?

To define a class

To create a loop

To include external modules or dependencies

To print output

19. What is the TypeScript convention for naming variables?

CamelCase

snake_case

kebab-case

PascalCase

20. Which programming language is TypeScript based on?

JavaScript

Java

Python

C++

21. Which operator is used to specify a type guard in TypeScript?

typeof

instanceof

All of the above

22. In TypeScript, how do you define a function?

func myFunction() {}

function myFunction() {}

method myFunction() {}

def myFunction() {}

23. Which TypeScript feature is used to describe the shape of an object, including its properties and their types?

Interface

Type assertion

Decorator

Mixin

24. What is the correct way to annotate a function return type in TypeScript?

function example(): returnType

function example() -> returnType

returnType function example()

function example() returns returnType

25. In TypeScript, what is the purpose of the 'try/catch' statement?

To define a class

To create a loop

To handle exceptions and errors

To print output

26. Which of the following is the correct way to define an interface for a function in TypeScript?

interface ExampleFunction { (param1: type1, param2: type2): returnType }

interface ExampleFunction { function(param1: type1, param2: type2): returnType }

function ExampleFunction(param1: type1, param2: type2): returnType;

type ExampleFunction = (param1: type1, param2: type2) => returnType;

27. How do you define a function in TypeScript?

function functionName() {}

const functionName = () => {}

def functionName() {}

method functionName() {}

28. Which data type is used to represent a collection of values in TypeScript?

array

list

set

collection

29. What is the purpose of the 'extends' keyword in generic constraints in TypeScript?

To inherit from another class

To limit the types that can be used with a generic type

To expand a generic type with additional properties

To check if a property exists in an object

30. Which is the correct way to define a class that implements an interface in TypeScript?

class ExampleClass implements ExampleInterface {}

class ExampleClass extends ExampleInterface {}

interface ExampleClass implements ExampleInterface {}

class ExampleClass: ExampleInterface {}

31. Which TypeScript data type is used for variables that may have a 'null' or 'undefined' value?

boolean

undefined

nullable

any

32. What is the purpose of TypeScript's 'readonly' modifier?

To define a class

To create a loop

To make a property or variable immutable

To print output

33. What is TypeScript's 'module' system used for?

To define a class

To create a loop

To organize and encapsulate code into reusable units

To print output

34. What is the TypeScript equivalent of 'console.log()' in JavaScript?

print()

log()

console.log()

display()

35. In TypeScript, what is the purpose of the 'namespace' keyword?

To define a class

To create a loop

To group related code into a named container

To print output

36. What is the purpose of TypeScript's 'typeof' operator?

To check the type of an expression

To declare a variable

To create an object

To define a function

37. What is the TypeScript convention for naming classes?

CamelCase

snake_case

kebab-case

PascalCase

38. Which of the following is a valid way to define a string variable in TypeScript?

string name = 'John';

let name: string = 'John';

const name = 'John';

name = 'John';

39. Which TypeScript keyword is used to declare a constant?

var

let

const

variable

40. Which TypeScript feature is used to apply metadata to classes, methods, or properties?

Access modifier

Type assertion

Decorator

Mixin

TypeScript MCQ Test 2