00:00:00 Closures are a bit tricky, and what you saw in the last lesson might have confused the hell out of you.

00:00:06 So let me give you a quick example.

00:00:07 I'll create a function called init.

00:00:11 It'll be an arrow function.

00:00:13 And within it, I'll declare a variable called hobby.

00:00:17 hobby will be equal to something like learning JavaScript.

00:00:21 Then, below it, I'll create another function called displayHobby, which will be equal to an arrow function that'll simply console log that hobby from the

00:00:33 external function.

00:00:34 Immediately after, I can call displayHobby like this, and outside of it, I'll run the init function.

00:00:42 In this example, the init function creates a local variable called hobby and a function called displayHobby.

00:00:51 The displayHobby function is an inner function that is defined inside of the init function.

00:00:57 However, since inner functions have access to the variables from the outer functions, displayHobby can access the variable hobby declared in the parent

00:01:08 function init.

00:01:09 Now, if we return the displayHobby function declaration instead of calling it right here, and then we set it to another variable,

00:01:17 like my func is equal to init, and then we try to call this new function, you'll see that the output is the same, but with a twist.

00:01:27 The displayHobby inner function is returned from the outer function before being executed.

00:01:34 At first glance, it may seem unintuitive that this code still works.

00:01:38 In some programming languages, the local variables within a function exist only for the duration of that function's execution.

00:01:46 However, in JavaScript, functions form closures.

00:01:52 And the closure is the combination of a function and the environment within which that function was declared.

00:01:59 This environment consists of any local variables that were created in scope at the time that the closure was created.

00:02:07 In this case, the my func is the reference to the instance of the function display hobby created when init is run.

00:02:17 The instance of display hobby maintains a reference to its environment within which the variable hobby exists.

00:02:26 For this reason, when MyFunk is invoked, the variable hobby remains available for it to use.

00:02:35 Closures are a powerful feature and they work by default.

00:02:39 They're baked into JavaScript.

00:02:40 So you never have to say, hey, turn this into a closure or let's use a closure here.

00:02:46 It just works, enabling you to write more flexible and modular code.

00:02:51 Understanding it will just help you write better JavaScript code.

00:02:55 It's complicated, you will rarely use it, but just being able to wrap your head around it is helpful.

00:03:01 You might get asked about what a closure is and to explain it within a JavaScript interview.

00:03:06 so it's better to know it than not.

00:03:08 But then once you actually land your job, trust me, you will not concern yourself with closures ever again, unless you have to return an inner function,

00:03:16 and then set it to another variable, and then execute it, and then that function has to use the variables outside of its scope.

00:03:23 Ah, so many ifs, it'll rarely happen, but I still wanted to share it with you, so if you need it one day, or if somebody mentions it,

00:03:31 you know what they're talking about.

00:03:33 But with that in mind, don't stress yourself about this.

00:03:37 There are much more important things in the JavaScript language, and the one we'll cover in the next module is the most important of them all.

00:03:45 So take a bit of a break, go for a walk, and when you clear up your mind from all the closures, hoistings, and scopes, come back and let's dive right into it.