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How can I use closures to create private variables in JavaScript?

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How can I use closures to create private variables in JavaScript?

Asked on Oct 07, 2025

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Closures in JavaScript allow you to create private variables by defining a function within another function, where the inner function has access to the outer function's scope. This technique is often used to encapsulate data and restrict access from the outside.

<!-- BEGIN COPY / PASTE -->
        function createCounter() {
            let count = 0; // Private variable

            return {
                increment: function() {
                    count++;
                    return count;
                },
                decrement: function() {
                    count--;
                    return count;
                },
                getCount: function() {
                    return count;
                }
            };
        }

        const counter = createCounter();
        console.log(counter.increment()); // 1
        console.log(counter.increment()); // 2
        console.log(counter.decrement()); // 1
        console.log(counter.getCount());  // 1
        <!-- END COPY / PASTE -->

Additional Comment:

The "createCounter" function defines a private variable "count" that is not accessible directly from outside.
The returned object contains methods that form closures over the "count" variable, allowing controlled access and modification.
Each call to "createCounter" creates a new closure with its own private "count" variable.
This pattern is useful for encapsulating state and behavior in a controlled manner.

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How can I use closures to create private variables in JavaScript?

Asked on Oct 07, 2025

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