Javascript/Typescript

Question 1

What is the purpose of JavaScript?

Answer 1

JavaScript is a programming language used to create dynamic and interactive content on websites.

Question 2

True or False: JavaScript is a statically typed language.

Answer 2

False

Question 3

Fill in the blank: In JavaScript, a variable declared with ‘let’ is _____ scoped.

Answer 3

block

Question 4

What is the output of ‘typeof null’ in JavaScript?

Answer 4

‘object’

Question 5

What does the ‘=== operator’ do in JavaScript?

Answer 5

It checks for both value and type equality.

Question 6

Which of the following is a JavaScript framework? A) Angular B) HTML C) CSS

Answer 6

A) Angular

Question 7

What is a closure in JavaScript?

Answer 7

A closure is a function that retains access to its lexical scope, even when the function is executed outside that scope.

Question 8

Define TypeScript.

Answer 8

TypeScript is a superset of JavaScript that adds static types and type checking.

Question 9

True or False: TypeScript can help catch errors at compile time.

Answer 9

True

Question 10

What is the file extension for TypeScript files?

Answer 10

.ts

Question 11

What is an interface in TypeScript?

Answer 11

An interface is a syntactical contract that defines the structure of an object.

Question 12

Fill in the blank: TypeScript supports _____ programming.

Answer 12

object-oriented

Question 13

What is the purpose of the ‘tsconfig.json’ file?

Answer 13

It specifies the compiler options and the files to be included in a TypeScript project.

Question 14

What is React Native?

Answer 14

React Native is a framework for building native mobile applications using React.

Question 15

True or False: React Native applications are written in JavaScript and rendered as native components.

Answer 15

True

Question 16

Which command is used to create a new React Native project?

Answer 16

npx react-native init ProjectName

Question 17

What is the main purpose of the ‘render’ method in React?

Answer 17

The ‘render’ method is used to describe what the UI should look like.

Question 18

Fill in the blank: In React, _____ is used to manage the component state.

Answer 18

useState

Question 19

What are props in React?

Answer 19

Props are inputs to a React component that allow data to be passed from parent to child components.

Question 20

What does ‘JSX’ stand for?

Answer 20

JavaScript XML

Question 21

What is the purpose of the ‘key’ prop in React lists?

Answer 21

The ‘key’ prop helps React identify which items have changed, are added, or are removed.

Question 22

What does the term ‘virtual DOM’ refer to in React?

Answer 22

The virtual DOM is a lightweight copy of the actual DOM that React uses to optimize rendering.

Question 23

What is the difference between state and props in React?

Answer 23

State is managed within the component, while props are passed down from parent components.

Question 24

True or False: TypeScript allows for optional parameters in functions.

Answer 24

True

Question 25

What is the purpose of the 'any' type in TypeScript?

Answer 25

The 'any' type allows a variable to hold any type of value, essentially opting out of type checking.

Question 26

What is the command to compile TypeScript files?

Answer 26

tsc

Question 27

Fill in the blank: In React Native, _____ is used to create styles.

Answer 27

StyleSheet

Question 28

What does the 'componentDidMount' lifecycle method do in React?

Answer 28

It is invoked immediately after a component is mounted, allowing for API calls or subscriptions.

Question 29

What is a functional component in React?

Answer 29

A functional component is a JavaScript function that returns a React element.

Question 30

True or False: In TypeScript, enums are a way to define a set of named constants.

Answer 30

True

Question 31

What is the purpose of the 'useEffect' hook in React?

Answer 31

The 'useEffect' hook is used for side effects in functional components, such as data fetching or subscriptions.

Question 32

What does the 'export' keyword do in TypeScript?

Answer 32

It allows a module to expose its variables, functions, or classes to be imported by other modules.

Question 33

Fill in the blank: In React Native, _____ is used for navigation between screens.

Answer 33

React Navigation

Question 34

What is the 'this' keyword in JavaScript?

Answer 34

'this' refers to the context in which a function is executed.

Question 35

What is a promise in JavaScript?

Answer 35

A promise is an object that represents the eventual completion (or failure) of an asynchronous operation.

Question 36

True or False: React components can only be class-based.

Answer 36

False

Question 37

What is destructuring in JavaScript?

Answer 37

Destructuring is a syntax that allows unpacking values from arrays or properties from objects into distinct variables.

Question 38

What does 'async/await' do in JavaScript?

Answer 38

It allows writing asynchronous code that looks synchronous, making it easier to read and maintain.

Question 39

Fill in the blank: To define a class in TypeScript, you use the _____ keyword.

Answer 39

class