JS Interview Question 12

Welcome to the 200 Interview Question Series of JavaScript! In this series, we’ll cover a wide range of JavaScript topics to help you prepare for your next interview.

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Today’s question is about closures in JavaScript. This is a common topic in JavaScript interviews, so it’s important to have a good understanding of how closures work.

The Question:

What is a closure in JavaScript and how does it work?

The Answer:

A closure is a function that has access to its own scope, as well as the scope of its parent function. This means that a closure can access variables and functions defined in its own scope, as well as those defined in the scope of the parent function.

When a function is defined within another function, the inner function has access to the variables and parameters of the outer function, even after the outer function has finished executing. This allows the inner function to “remember” the environment in which it was created, and to access those variables and parameters even when it is called outside of the scope of the parent function.

Closures are commonly used in JavaScript to create private variables and to implement data hiding and encapsulation. They are also used in event handling and callback functions, as they allow you to maintain access to the variables and parameters of the parent function, even when the event or callback function is executed at a later time.

Conclusion:

Understanding closures is an important concept in JavaScript, and is often tested in interviews. It’s important to be able to explain what a closure is, how it works, and to provide examples of how they can be used in practice.

That’s all for today’s interview question! Be sure to check back for the next question in our 200 Interview Question Series of JavaScript.