CODEWITHSUNDEEP
javascriptclosures
Karias Bolster
Karias Bolster

Reputation: 1035

Javascipt emulates private variables but javascript are already private because of scope?

I've been studying javascript just now and i'm currently in closures. It is said that closure emulates private variables. But aren't variables only accessible on their own scope making them private by default? Given this example

function manageSalary () {
    let salary = 0;
    function updateSalary(amount) {
        salary += amount;
    }
    return {
        raise: function(amount) {
            updateSalary(amount);
        },
        deduct: function(amount) {
            updateSalary(amount);
        },
        current: function () {return salary}
    }
};

How exactly does closure makes the salary variable private in this example? Isn't salary already private since you cant access it outside this manageSalary? What I understood from this example rather is that closure emulates private methods instead.

Upvotes: 1

Views: 30

Answers (1)

T.J. Crowder
T.J. Crowder

Reputation: 1074829

Tackling your questions slightly out of order:

Isn't salary already private since you cant access it outside this manageSalary?

Yes.

How exactly does closure makes the salary variable private in this example?

The closures don't make salary private. As you said, it's already private. The closures take advantage of the fact salary is private but they (the closures) aren't. The return value of manageSalary is an object with those closures on it as (effectively) methods. The methods have access to salary, but nothing else has access to it.

Upvotes: 2

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