What is JavaScript, and how does it differ from Java?
Ans: JavaScript is a dynamic, high-level, and interpreted programming language primarily used for front-end web development. It has no relation to Java other than a similar name.

What are the different data types in JavaScript?
Ans: JavaScript has several data types, including numbers, strings, booleans, objects, arrays, null, and undefined.

Explain the difference between null and undefined in JavaScript.
Ans: null represents the intentional absence of any value or object, while undefined indicates a variable that has been declared but hasn't been assigned a value yet.

What is a closure in JavaScript?
Ans: A closure is a function that has access to the variables from its outer (enclosing) function, even after the outer function has finished executing. It "closes over" its surrounding lexical scope.

What is the event loop in JavaScript, and how does it work?
Ans: The event loop is a crucial part of JavaScript's concurrency model. It manages asynchronous operations by continuously checking the message queue for tasks to execute, allowing for non-blocking operations.

Explain the concept of hoisting in JavaScript.
Ans: Hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase, which allows you to use them before they're declared.

What is the difference between let, const, and var in variable declaration?
Ans: let and const are block-scoped, and var is function-scoped. const variables cannot be reassigned after declaration, while let and var can.

How can you handle asynchronous operations in JavaScript?
Ans: You can handle asynchronous operations in JavaScript using callbacks, promises, or async/await. Promises are a common choice for managing asynchronous code.

What is the purpose of the this keyword in JavaScript?
Ans: The this keyword refers to the current execution context and can vary depending on how a function is called. In global scope, it refers to the global object (e.g., window in browsers).

Explain the Same-Origin Policy and how it relates to JavaScript.
Ans: The Same-Origin Policy is a security feature in web browsers that restricts web pages from making requests to domains other than their own origin (protocol, domain, and port). JavaScript adheres to this policy to prevent cross-site scripting (XSS) attacks.