CODEWITHSUNDEEP
javascriptfunction
Camilo Sanchez
Camilo Sanchez

Reputation: 1282

What is the difference between a closure and a module?

I know that a module like this one:

function User(){
    var username, password;

    function doLogin(user, pw){
        username = user;
        password = pw;
    };
    var publicAPI = {
        login: doLogin
    };
    return publicAPI;
}

has a closure inside of it: doLogin, and is remembering the values of the variables username and password that are inside User, what makes this a "closure". What I don't quite understand is if whenever we use a closure we are using the module pattern? or as soon as I save the function of the User in a variable like var User = function(){... is not a module... Please bear in mind I'm learning js.

Upvotes: 9

Views: 2861

Answers (2)

Ben Aston
Ben Aston

Reputation: 55729

You have implemented a factory function for Users.

You are "almost" using the revealing module pattern. Most people would say the revealing module pattern would need to be invoked immediately. Module patterns are usually used for code organisation. What you have here instead is an object factory.

Closures are used by the (revealing) module pattern (and others) to achieve the encapsulation of private state.

A closure is created whenever a function is defined. They are a language feature of JavaScript to make working with functions easier.

Upvotes: 6

Ramanlfc
Ramanlfc

Reputation: 8354

Closures are a way to close over(or capture) information or state from the enclosing scope. Basically it is a means of extending the lifetime of a variable.

Modules are a way to hide the implementation and state from outside world.

So, doLogin() is closing over both username and password and thus increasing their lifetime. And object refereed to by publicAPI is hiding the implementation of doLogin() from the user

Upvotes: 0

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