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typescript MCQ Mock Test

75 Questions • 20 Seconds / Question

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Q 1/75

typescript MCQs with Answers

1. Which is a generic example?

A. Array<number>
B. number[]
C. any[]
D. object[]

Correct: A

Explanation: Array<number> is generic.

2. Which file extension is used for TypeScript?

A. .js
B. .jsx
C. .ts
D. .tsx

Correct: C

Explanation: .ts is the standard TypeScript file extension.

3. null and undefined are same?

A. Yes
B. No
C. Sometimes
D. Only in JS

Correct: B

Explanation: They are different types.

4. Which keyword implements interface?

A. extends
B. implements
C. uses
D. inherit

Correct: B

Explanation: implements is used to implement interface.

5. Which keyword creates an instance?

A. new
B. create
C. init
D. make

Correct: A

Explanation: new creates an instance.

6. typeof operator returns?

A. Value
B. Runtime type
C. Type of variable
D. Function result

Correct: C

Explanation: typeof returns type.

7. unknown is safer than any?

A. Yes
B. No
C. Sometimes
D. Never

Correct: A

Explanation: unknown requires type checking.

8. Which command compiles TypeScript?

A. node
B. npm
C. tsc
D. tsrun

Correct: C

Explanation: tsc is the TypeScript compiler.

9. tsconfig.json is used for?

A. Runtime config
B. Compiler options
C. Server config
D. Database config

Correct: B

Explanation: tsconfig configures compiler.

10. Abstract classes can be instantiated?

A. Yes
B. No
C. Sometimes
D. Only once

Correct: B

Explanation: Abstract classes cannot be instantiated.

11. Namespaces exist at runtime?

A. Yes
B. No
C. Sometimes
D. Only in dev

Correct: A

Explanation: Namespaces exist in JS output.

12. Which keyword imports module?

A. import
B. require
C. include
D. load

Correct: A

Explanation: import is used in TypeScript.

13. await works with?

A. Functions
B. Promises
C. Classes
D. Interfaces

Correct: B

Explanation: await works with promises.

14. Which flag enables strict?

A. --safe
B. --strict
C. --secure
D. --typed

Correct: B

Explanation: --strict enables strict mode.

15. .d.ts files contain?

A. Runtime code
B. Type definitions
C. Tests
D. Configs

Correct: B

Explanation: .d.ts contains type definitions.

16. Partial<T> does?

A. Makes all optional
B. Makes all required
C. Removes properties
D. Freezes object

Correct: A

Explanation: Partial makes all properties optional.

17. Pick<T,K> does?

A. Select properties
B. Remove properties
C. Merge types
D. Clone object

Correct: A

Explanation: Pick selects properties.

18. @types packages provide?

A. Runtime code
B. Type definitions
C. Docs
D. Tests

Correct: B

Explanation: @types provides typings.

19. What are enums?

A. Functions
B. Objects
C. Named constants
D. Classes

Correct: C

Explanation: Enums define named constants.

20. Which type represents an array of numbers?

A. number[]
B. Array<string>
C. string[]
D. any[]

Correct: A

Explanation: number[] defines an array of numbers.

21. Generics provide?

A. Code duplication
B. Type safety
C. Runtime checks
D. Compilation errors

Correct: B

Explanation: Generics provide type safety.

22. Which keyword exports module?

A. export
B. module
C. expose
D. public

Correct: A

Explanation: export exposes module.

23. Which type represents true or false?

A. number
B. string
C. boolean
D. any

Correct: C

Explanation: boolean represents true or false.

24. Which keyword defines abstract method?

A. abstract
B. virtual
C. override
D. method

Correct: A

Explanation: abstract keyword defines abstract method.

25. Which type allows any value?

A. any
B. unknown
C. never
D. void

Correct: A

Explanation: any disables type checking.

26. Example of union type?

A. string & number
B. string | number
C. string + number
D. string / number

Correct: B

Explanation: Union allows either string or number.

27. Type casting changes value?

A. Yes
B. No
C. Sometimes
D. Only numbers

Correct: B

Explanation: Casting does not change value.

28. Tuple order matters?

A. Yes
B. No
C. Sometimes
D. Only in strict mode

Correct: A

Explanation: Tuple order is fixed.

29. TypeScript supports OOP?

A. Yes
B. No
C. Partial
D. Only classes

Correct: A

Explanation: TypeScript supports OOP.

30. Which flag checks null?

A. strictNullChecks
B. nullCheck
C. checkNull
D. safeNull

Correct: A

Explanation: strictNullChecks checks null.

31. keyof operator returns?

A. Values
B. Keys
C. Types
D. Indexes

Correct: B

Explanation: keyof returns keys.

32. Infer keyword is used in?

A. Conditional types
B. Interfaces
C. Enums
D. Classes

Correct: A

Explanation: infer is used in conditional types.

33. Decorators are?

A. Functions
B. Metadata
C. Annotations
D. All of the above

Correct: D

Explanation: Decorators add metadata.

34. Required<T> does?

A. Makes optional
B. Makes required
C. Removes readonly
D. Freezes object

Correct: B

Explanation: Required makes all required.

35. Which access modifier is default?

A. private
B. protected
C. public
D. internal

Correct: C

Explanation: public is default.

36. Readonly<T> does?

A. Freeze object
B. Remove readonly
C. Make mutable
D. Convert type

Correct: A

Explanation: Readonly prevents modification.

37. async function returns?

A. Promise
B. Value
C. Callback
D. Observable

Correct: A

Explanation: async returns Promise.

38. Which keyword defines optional parameters?

A. ?
B. !
C. *
D. &

Correct: A

Explanation: ? makes a parameter optional.

39. never represents?

A. Any value
B. No value
C. Null value
D. Undefined

Correct: B

Explanation: never represents no value.

40. TypeScript works with JS?

A. No
B. Yes
C. Sometimes
D. Only ES6

Correct: B

Explanation: TypeScript works with JS.

41. strict mode enables?

A. More checks
B. Less checks
C. Faster code
D. Smaller bundle

Correct: A

Explanation: Strict mode enables checks.

42. Decorators are enabled using?

A. tsconfig.json
B. package.json
C. webpack
D. babel

Correct: A

Explanation: Decorators enabled in tsconfig.

43. Default enum values start from?

A. 0
B. 1
C. -1
D. Undefined

Correct: A

Explanation: Enums start from 0 by default.

44. Who developed TypeScript?

A. Google
B. Facebook
C. Microsoft
D. Amazon

Correct: C

Explanation: TypeScript was developed by Microsoft.

45. Which keyword defines a class?

A. class
B. struct
C. object
D. define

Correct: A

Explanation: class keyword defines a class.

46. Default parameter values are supported?

A. Yes
B. No
C. Only in ES5
D. Only in strict mode

Correct: A

Explanation: TypeScript supports default parameters.

47. What is an interface used for?

A. Runtime logic
B. Type checking
C. Styling
D. Database schema

Correct: B

Explanation: Interfaces define object shapes.

48. What is a tuple?

A. Array with fixed types
B. Dynamic array
C. Object
D. Map

Correct: A

Explanation: Tuples have fixed length and types.

49. Which keyword is used for inheritance?

A. extends
B. implements
C. inherits
D. derives

Correct: A

Explanation: extends is used for inheritance.

50. Interfaces exist at runtime?

A. Yes
B. No
C. Sometimes
D. Only in production

Correct: B

Explanation: Interfaces are removed during compilation.

51. Arrow functions support types?

A. Yes
B. No
C. Sometimes
D. Only return

Correct: A

Explanation: Arrow functions support types.

52. Best practice in TypeScript?

A. Use any
B. Avoid types
C. Enable strict mode
D. Ignore errors

Correct: C

Explanation: Strict mode is best practice.

53. Which target outputs ES6?

A. target: es5
B. target: es6
C. target: es3
D. target: latest

Correct: B

Explanation: es6 outputs ES6.

54. TypeScript code is compiled into?

A. Java bytecode
B. Machine code
C. JavaScript
D. Binary

Correct: C

Explanation: TypeScript is compiled into JavaScript.

55. Type errors occur at?

A. Runtime
B. Compile time
C. Both
D. Never

Correct: B

Explanation: Type errors occur at compile time.

56. How do you specify return type?

A. After function name
B. After parameters
C. After colon
D. Before function

Correct: C

Explanation: Return type is specified after colon.

57. Omit<T,K> does?

A. Select properties
B. Remove properties
C. Merge types
D. Extend type

Correct: B

Explanation: Omit removes properties.

58. Type assertion tells compiler?

A. Change value
B. Ignore type
C. Assume a type
D. Convert value

Correct: C

Explanation: Type assertion assumes a type.

59. Generic syntax uses?

A. <>
B. {}
C. []
D. ()

Correct: A

Explanation: <> is used for generics.

60. TypeScript improves performance?

A. At runtime
B. At compile time
C. Both
D. None

Correct: B

Explanation: TypeScript improves dev-time safety.

61. readonly means?

A. Cannot be read
B. Cannot be modified
C. Cannot be created
D. Cannot be accessed

Correct: B

Explanation: readonly prevents modification.

62. Which keyword declares a variable?

A. var
B. let
C. const
D. All of the above

Correct: D

Explanation: All can declare variables in TypeScript.

63. Which type represents no return value?

A. null
B. void
C. never
D. undefined

Correct: B

Explanation: void represents no return value.

64. Intersection types use which operator?

A. |
B. &
C. +
D. *

Correct: B

Explanation: Intersection types use & operator.

65. Which is not OOP feature?

A. Inheritance
B. Encapsulation
C. Compilation
D. Polymorphism

Correct: C

Explanation: Compilation is not OOP.

66. Function that throws error returns?

A. void
B. any
C. never
D. undefined

Correct: C

Explanation: Functions that never return use never.

67. Mapped types are used for?

A. Transforming types
B. Runtime loops
C. API calls
D. Database mapping

Correct: A

Explanation: Mapped types transform types.

68. Which modifier restricts access to class?

A. private
B. public
C. protected
D. readonly

Correct: A

Explanation: private restricts access.

69. What is a union type?

A. Multiple interfaces
B. Combination of types using |
C. Inheritance
D. Overloading

Correct: B

Explanation: Union type uses | operator.

70. Which file allows JS?

A. allowJs
B. checkJs
C. jsMode
D. enableJs

Correct: A

Explanation: allowJs allows JS files.

71. TypeScript uses which module system?

A. CommonJS
B. ES Modules
C. AMD
D. All of the above

Correct: D

Explanation: TypeScript supports multiple systems.

72. Which syntax is valid?

A. value as string
B. <string>value
C. Both
D. None

Correct: C

Explanation: Both syntaxes are valid.

73. Namespaces are used to?

A. Group code
B. Execute code
C. Compile code
D. Deploy code

Correct: A

Explanation: Namespaces group code logically.

74. What is TypeScript?

A. A database
B. A JavaScript framework
C. A superset of JavaScript
D. A CSS library

Correct: C

Explanation: TypeScript is a superset of JavaScript that adds static typing.

75. Conditional types use?

A. extends
B. implements
C. typeof
D. instanceof

Correct: A

Explanation: Conditional types use extends.

typescript MCQ Mock Test

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typescript MCQs with Answers

1. Which is a generic example?

2. Which file extension is used for TypeScript?

3. null and undefined are same?

4. Which keyword implements interface?

5. Which keyword creates an instance?

6. typeof operator returns?

7. unknown is safer than any?

8. Which command compiles TypeScript?

9. tsconfig.json is used for?

10. Abstract classes can be instantiated?

11. Namespaces exist at runtime?

12. Which keyword imports module?

13. await works with?

14. Which flag enables strict?

15. .d.ts files contain?

16. Partial<T> does?

17. Pick<T,K> does?

18. @types packages provide?

19. What are enums?

20. Which type represents an array of numbers?

21. Generics provide?

22. Which keyword exports module?

23. Which type represents true or false?

24. Which keyword defines abstract method?

25. Which type allows any value?

26. Example of union type?

27. Type casting changes value?

28. Tuple order matters?

29. TypeScript supports OOP?

30. Which flag checks null?

31. keyof operator returns?

32. Infer keyword is used in?

33. Decorators are?

34. Required<T> does?

35. Which access modifier is default?

36. Readonly<T> does?

37. async function returns?

38. Which keyword defines optional parameters?

39. never represents?

40. TypeScript works with JS?

41. strict mode enables?

42. Decorators are enabled using?

43. Default enum values start from?

44. Who developed TypeScript?

45. Which keyword defines a class?

46. Default parameter values are supported?

47. What is an interface used for?

48. What is a tuple?

49. Which keyword is used for inheritance?

50. Interfaces exist at runtime?

51. Arrow functions support types?

52. Best practice in TypeScript?

53. Which target outputs ES6?

54. TypeScript code is compiled into?

55. Type errors occur at?

56. How do you specify return type?

57. Omit<T,K> does?

58. Type assertion tells compiler?

59. Generic syntax uses?

60. TypeScript improves performance?

61. readonly means?

62. Which keyword declares a variable?

63. Which type represents no return value?

64. Intersection types use which operator?

65. Which is not OOP feature?

66. Function that throws error returns?

67. Mapped types are used for?

68. Which modifier restricts access to class?

69. What is a union type?

70. Which file allows JS?

71. TypeScript uses which module system?

72. Which syntax is valid?

73. Namespaces are used to?

74. What is TypeScript?

75. Conditional types use?