JavaScript Interview Question and Answers
JavaScript Interview Question and Answers: JavaScript is a high-level, dynamic, and interpreted programming language that is primarily used for creating interactive web applications and user interfaces. It is one of the most popular programming languages in the world, and its versatility and flexibility make it an essential tool for front-end and back-end web development.
JavaScript Interview Question and Answers: JavaScript can be used to add dynamic and interactive elements to web pages, such as form validation, animations, and user interface effects. Additionally, JavaScript is often used in conjunction with other web technologies such as HTML and CSS to create complex web applications that are fast, responsive, and user-friendly. With the advent of frameworks such as React, Angular, and Vue, JavaScript has become an even more powerful tool for web development, allowing developers to create complex applications with ease, Here we are Providing Important JavaScript Interview Question and Answers.
JavaScript Interview Question and Answers;
Question: 1. What is JavaScript?
Answer: JavaScript is a high-level, dynamic, and interpreted programming language that is primarily used for creating interactive web applications and user interfaces.
Question: 2. What is the difference between let, const, and var?
Answer: let and const are block-scoped variables that were introduced in ES6, while var is function-scoped. let can be reassigned, while const cannot be reassigned. It is recommended to use const for values that do not need to be reassigned, and let for values that may need to be reassigned.
Question: 3. What are closures in JavaScript?
Answer: Closures are functions that have access to variables in their outer lexical environment, even after that environment has returned. They are created by declaring a function inside another function.
Question: 4. What is the event loop in JavaScript?
Answer: The event loop is a mechanism in JavaScript that allows for asynchronous code execution. It continuously checks the call stack and task queue, and when the call stack is empty, it takes the first task from the task queue and executes it.
Question: 5. What is the difference between == and ===?
Answer: == is a loose comparison operator that compares values for equality after converting data types if necessary, while === is a strict comparison operator that compares values for equality without converting data types.
Question: 6. What is hoisting in JavaScript?
Answer: Hoisting is a behavior in JavaScript where variable and function declarations are moved to the top of their respective scopes, regardless of where they are actually declared in the code.
Question: 7. What are callbacks in JavaScript?
Answer: Callbacks are functions that are passed as arguments to other functions and are executed when certain events occur. They are often used in asynchronous code to handle the results of operations that take a long time to complete.
Question: 8. What is the difference between synchronous and asynchronous code?
Answer: Synchronous code is executed in sequence, and each line of code waits for the previous line to complete before it is executed. Asynchronous code is executed out of order, and code that takes a long time to complete does not block the execution of other code. It often uses callbacks or promises to handle the results of long-running operations
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