Which of the following is the correct way to declare a JavaScript variable?
a) var x;
b) int x;
c) let x;
d) Both a and c
Which of the following is used to define a function in JavaScript?
a) function()
b) func()
c) def()
d) method()
What does the alert() function do in JavaScript?
a) Displays a pop-up message
b) Redirects to another page
c) Logs the message to the console
d) Refreshes the webpage
Which of the following methods is used to add an element to the end of an array in JavaScript?
a) push()
b) pop()
c) shift()
d) unshift()
What is the purpose of console.log() in JavaScript?
a) To print output to the webpage
b) To display an alert message
c) To log messages in the console for debugging
d) To update the DOM
Which of the following is NOT a primitive data type in JavaScript?
a) String
b) Number
c) Object
d) Boolean
How do you create an object in JavaScript?
a) var obj = {};
b) var obj = ();
c) var obj = [];
d) var obj = new Object();
What will console.log(5 + ‘5’) output in JavaScript?
a) 55
b) 10
c) Error
d) 5 5
Which of the following is the correct syntax to access an HTML element with the id “myElement” in JavaScript?
a) document.getElementById(“myElement”)
b) document.getElement(“myElement”)
c) getElementById(“myElement”)
d) document.getElementByClassName(“myElement”)
Which method is used to remove the last element of an array in JavaScript?
a) pop()
b) push()
c) shift()
d) unshift()
What does the setTimeout() function do in JavaScript?
a) Executes a function after a specified delay
b) Loops a function infinitely
c) Delays the loading of a webpage
d) Stops the execution of a function
Which of the following is a front-end JavaScript framework?
a) Django
b) Laravel
c) React
d) Flask
Which of the following JavaScript frameworks is primarily used for building mobile apps?
a) React
b) Angular
c) Vue
d) React Native
What is the use of localStorage in JavaScript?
a) To store data on the client-side persistently
b) To store data temporarily during a session
c) To store data on the server-side
d) To store data in cookies
Which of the following is true about promises in JavaScript?
a) A promise is a placeholder for a value that is available now
b) A promise is a placeholder for a value that is available in the future
c) A promise is a method used to handle errors
d) Promises are not used in asynchronous JavaScript
Which of the following is used to handle routing in a React application?
a) Redux
b) React-Router
c) React-Query
d) Next.js
What does JSX stand for in React?
a) JavaScript XML
b) JavaScript Extended
c) JavaScript Syntax Extension
d) JavaScript Style XML
What is the use of ngIf in Angular?
a) To repeat elements in the DOM
b) To conditionally render elements in the DOM
c) To bind event listeners
d) To manipulate styles dynamically
Which of the following is the default data binding method in Angular?
a) Two-way binding
b) One-way binding
c) Event binding
d) Property binding
What is the purpose of v-for in Vue.js?
a) To conditionally render elements
b) To loop over an array and render items
c) To bind events
d) To modify data in the DOM
Which JavaScript framework is known for its “MVVM” architecture?
a) React
b) Angular
c) Vue.js
d) Ember.js
What is the main difference between let and var in JavaScript?
a) let is function-scoped, while var is block-scoped
b) var is function-scoped, while let is block-scoped
c) let cannot be redeclared, while var can
d) var is a better choice for modern code
Which of the following methods is used to update the state in a React component?
a) setState()
b) updateState()
c) changeState()
d) modifyState()
What is the main purpose of Webpack in a JavaScript project?
a) To manage APIs
b) To bundle JavaScript files
c) To optimize performance
d) To manage databases
Which of the following is true about the virtual DOM in React?
a) It is a representation of the actual DOM in memory
b) It is slower than the actual DOM
c) It is not used for rendering React components
d) It directly manipulates the real DOM
What does the ngModel directive in Angular bind?
a) User input to a property
b) Events to a function
c) CSS styles to elements
d) API data to a variable
Which of the following is a popular JavaScript library for state management in React applications?
a) Vuex
b) Redux
c) MobX
d) Both b and c
What is the purpose of useEffect() in React?
a) To render the component
b) To update the component’s state
c) To run side effects in function components
d) To handle events
Which of the following is used to send data from a Vue component to the parent component?
a) props
b) events
c) methods
d) state
Which CSS framework is most commonly used with JavaScript for front-end development?
a) Bootstrap
b) Tailwind CSS
c) Foundation
d) Bulma
Which of the following methods is used to remove the first element from an array in JavaScript?
a) shift()
b) pop()
c) slice()
d) unshift()
What is the correct way to reference a class in CSS?
a) #class-name
b) .class-name
c) &class-name
d) class-name{}
Which JavaScript function is used to check if a variable is an array?
a) isArray()
b) checkArray()
c) Array.isArray()
d) validateArray()
