1. What is TypeScript?
a. A superset of JavaScript
b. A subset of JavaScript
c. A completely different language
d. A version of JavaScript
Answer: a. A superset of JavaScript
2. What is the primary goal of TypeScript?
a. To replace JavaScript
b. To enhance JavaScript by adding static types
c. To make JavaScript run faster
d. To add new features to JavaScript
Answer: b. To enhance JavaScript by adding static types
3. Which keyword is used to declare a variable with a specific type in TypeScript?
a. var
b. let
c. const
d. none of the above
Answer: d. none of the above (use 'let', 'const', or 'var' followed by a colon to specify the type)
4. In TypeScript, what does the 'any' type signify?
a. A variable of any type
b. An undefined type
c. A variable of a fixed type
d. A variable of an unknown type
Answer: a. A variable of any type
5. What does TypeScript use to catch common errors during development?
a. Static analysis
b. Dynamic analysis
c. Runtime errors
d. Compile-time errors
Answer: d. Compile-time errors
6. Which of the following is a valid TypeScript variable declaration?
a. var x: number = 5;
b. let y = "Hello";
c. const z: boolean;
d. All of the above
Answer: a. var x: number = 5; and b. let y = "Hello;"
7. How can you define an interface in TypeScript?
a. Using the 'class' keyword
b. Using the 'interface' keyword
c. Using the 'type' keyword
d. Using the 'implements' keyword
Answer: b. Using the 'interface' keyword
8. What is the main difference between 'interface' and 'type' in TypeScript?
a. 'type' can be used for defining objects, while 'interface' cannot.
b. 'interface' can be used for defining objects, while 'type' cannot.
c. There is no difference; they are interchangeable.
d. 'type' is used for defining classes, while 'interface' is used for defining objects.
Answer: a. 'type' can be used for defining objects, while 'interface' cannot.
9.Which TypeScript feature is used to define the type of 'this' in a function?
a. 'this' keyword
b. 'self' keyword
c. 'that' keyword
d. 'context' keyword
Answer: a. 'this' keyword
10. What is the purpose of the 'never' type in TypeScript?
a. To represent a value that never changes
b. To represent a value that will always be 'null'
c. To indicate that a function never returns
d. To represent a variable of unknown type
Answer: c. To indicate that a function never returns
11. What is TypeScript's 'type assertion' used for?
a. To convert a variable to a different type
b. To perform arithmetic operations on variables
c. To assign a value to a variable
d. To check if a variable is null
Answer: a. To convert a variable to a different type
12. What does the 'tsconfig.json' file in a TypeScript project do?
a. It specifies the TypeScript version to use.
b. It configures the project's compiler options and settings.
c. It defines the project's runtime environment.
d. It contains code for the project.
Answer: b. It configures the project's compiler options and settings.
13. How can you enable strict type-checking in TypeScript?
a. Use the '--strict' flag in the 'tsc' command.
b. Set the 'strict' option to 'true' in 'tsconfig.json'.
c. Use the 'strict' keyword in your code.
d. Both a and b
Answer: d. Both a and b
14. What is the purpose of 'tslint' in TypeScript?
a. To compile TypeScript code
b. To format TypeScript code
c. To check code quality and enforce coding standards
d. To run unit tests
Answer: c. To check code quality and enforce coding standards
15. How do you import a module in TypeScript?
a. Using the 'import' keyword
b. Using the 'include' keyword
c. Using the 'require' keyword
d. Using the 'use' keyword
Answer: a. Using the 'import' keyword
16. What does TypeScript use to handle asynchronous operations?
a. Callbacks
b. Promises
c. Observables
d. All of the above
Answer: d. All of the above
17. What is a 'decorator' in TypeScript?
a. A design pattern
b. A type of module
c. A function that modifies a class or class member
d. A built-in TypeScript class
Answer: c. A function that modifies a class or class member
18. Which TypeScript feature helps you catch typos and errors when accessing object properties?
a. Optional chaining (?.)
b. Template literals
c. Destructuring
d. Object literals
Answer: a. Optional chaining (?.)
19. What does the 'union' type allow in TypeScript?
a. A variable to have multiple types
b. A variable to have only one specific type
c. A variable to have both 'number' and 'string' types
d. A variable to have no type
Answer: a. A variable to have multiple types
20. What is 'TypeScript Declaration Files' used for?
a. To declare the types of JavaScript libraries
b. To declare global variables
c. To declare variables within a function
d. To define the type of a variable
Answer: a. To declare the types of JavaScript libraries
21. How do you define an array in TypeScript?
a. const arr = [1, 2, 3];
b. const arr: array = [1, 2, 3];
c. const arr: number[] = [1, 2, 3];
d. const arr: Array = [1, 2, 3];
Answer: c. const arr: number[] = [1, 2, 3]; and d. const arr: Array = [1, 2, 3];
22. What is the purpose of 'readonly' in TypeScript?
a. To make a property writable
b. To make a property read-only
c. To make a variable mutable
d. To define a constant
Answer: b. To make a property read-only
23. Which operator is used to concatenate strings in TypeScript?
a. +
b. &
c. ,
d. :
Answer: a. +
24. What does the 'as' keyword do in TypeScript?
a. It's used for type assertion
b. It's used for arithmetic operations
c. It's used to define an alias for a type
d. It's used for string concatenation
Answer: a. It's used for type assertion
25. How do you declare a tuple type in TypeScript?
a. type MyTuple = (string, number);
b. type MyTuple = [string, number];
c. type MyTuple = { string, number };
d. type MyTuple = ;
Answer: b. type MyTuple = [string, number];
26. What is 'Type Narrowing' in TypeScript?
a. The process of converting one type to another
b. The process of narrowing down the type of a variable based on its usage
c. The process of defining types for variables
d. The process of casting types in TypeScript
Answer: b. The process of narrowing down the type of a variable based on its usage
27. How can you define a function type in TypeScript?
a. type MyFunction = (param1: number, param2: string) => void;
b. type MyFunction = function(param1: number, param2: string): void;
c. type MyFunction(param1: number, param2: string): void;
d. type MyFunction: (param1: number, param2: string) => void;
Answer: a. type MyFunction = (param1: number, param2: string) => void;
28. Which TypeScript feature is used to enforce that a function is always used with a 'try-catch' block?
a. 'async' keyword
b. 'never' type
c. 'void' type
d. 'finally' keyword
Answer: b. 'never' type
29. How do you declare a constant in TypeScript?
a. const myConst: number;
b. const myConst = 42;
c. let myConst = 42;
d. const myConst: number = 42;
Answer: b. const myConst = 42; and d. const myConst: number = 42;
30. What is the purpose of 'strictNullChecks' in TypeScript?
a. To allow null values for all variables
b. To disallow null and undefined values by default
c. To enforce null checks for specific variables
d. To define null as a valid type
Answer: b. To disallow null and undefined values by default
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