JavaScript closures compared to instances of classes

Exploring the realm of theoretical programming rather than practical applications, my focus has turned towards closures in JavaScript. In essence, a closure is a function with its own exclusive set of variables that are not accessible to copies of the function. Each closure has its own var a.

I can't help but notice that closures operate much like instances of the same class, each having its own members and properties. Just as a method of an instance can only access the var a within that specific instance.

Do closures offer capabilities beyond what OOP provides? Are they able to produce cleaner code or offer distinct advantages compared to traditional object-oriented programming?

It seems like people tout closures as one of JavaScript's greatest features, but I view them simply as a byproduct of creating a function with persistent scope. Am I missing something important here?

EDIT

To steer clear of opinion-based responses, let's rephrase the question for a more concrete discussion:

What unique abilities do closures possess that cannot be achieved solely through OOP in JavaScript?

Answer №1

Through extensive research, I recently uncovered a key advantage of closures that had previously eluded me.

When utilizing Object-Oriented Programming in JavaScript, the absence of private variables is noticeable (although as a solitary developer, it hadn't been necessary for me thus far). Object members are generally easily accessible within their scope.

However, closures provide a means to keep variables accessible only within the scope in which they are defined. Any efforts to access these variables outside of the scope will lead to encountering a different variable with the same name in that scope. Without appropriate getter/setter methods offered by the scope, there is no way to access or modify these variables from external sources. This creates an effective method for implementing private variables and encapsulating data!

Furthermore, closures prevent any confusion or interference with similarly named variables outside of the closure's scope, reinforcing their usefulness.

This concept of "encapsulation" achieved through closures surpasses traditional JavaScript OOP practices.

Answer №2

When I require numerous instances of an item, I employ classes or instantiable objects. Conversely, for scenarios where only a single instance is necessary, I typically turn to function closures in order to maintain the privacy of internal variables.

However, it's important to note that closures serve as more than just a substitution for a class; they also excel at "closing over" variables from external scopes, a technique frequently employed in JavaScript development.

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