So far, this is one of the best descriptions of closures I've come across. However, when you explain closures, it's worth doing a brief review of function syntax. I think what confuses most people about closures is the return statement of the outer function, what exactly is being returned. Most people believe the return statement is returning what is evaluated in the inner function, when, in fact, it is returning the function itself along with its lexical scope. Note, that in the return statement, the displayName function does not have a set of parentheses following it. Remember that a function without parentheses is the function itself -- all of its syntax, instructions, lexical scope-- and NOT the value of the evaluated function, as most people might think. In this example, when the inner function is passed to the global scope, it gets stored to a variable in much the same manner as a function expression. As with a function expression, to invoke it, you place parentheses after it to call its respective function, and it evaluates. I've have yet to see anyone explain this in a video. Their is an assumption that the viewer already understands this concept. The problem with learning closures is that by the time a student gets to them, they are so used to the syntax of function declarations, that they take them for granted and probably do not realize that only the function name is used in the return statement, and not a function call.

After writing JavaScript code for the last couple of years now I understand what exactly is javascript closure. You made my day bro. Thanks alot.

I am still confused but less confused than after my 30min lecture + activities on this. Thank you for being an excellent teacher!

Thanks Beau,. After 2 years as a JS engineer, finally understood closures watching a 6 years old video

Well you always manage to explain it the way I can understand it. So to everyone else, we all learn different! for me Beau is the way..

Awesome example! This helped me a ton when you related it to an object-oriented class with private data and public and protected functions

Wow, just spend at least the past 2 hours trying to understand closures watching a few 20+ minute videos, reading up, etc. This video is literally the shortest content out of any of them but it is the only one that is clear and logical and it definitely helped me understand closures. Thank you!

Thanks for the great video and tutorial. This is how I like to think of closures. Please feel free to correct me if my understanding of some concepts aren't correct as I'm just learning about closures myself. /* The closure of a function is the function(s) its enclosed in and the inner function(s) has access to the variables defined in those closures even after those functions are no longer on the execution stack. Paste and run the below in Google Chrome console and drill down into the scopes to check the closures out. In the below example the inner function is enclosed in speak function hence it's closure is the function speak. If speak itself was within another outer function then inner function has TWO closures the speak function as well as the outer one enclosing speak. */ function speak(greeting) { var inner = function (name) { console.log(greeting + " " + name); } return inner } var theGreeting = speak("Hello"); console.log(theGreeting("Adam")); console.dir(theGreeting);

A month in on this stuff and I am still completely lost

so, the private variable in the parent container function is modified by the child container function? Ex. function parentFunction() { let counter = 0 function childFunction() { console.log("counter",counter) console.log("counter increment",counter+=1) } return childFunction } let result = parentFunction() result() result() result()

It's when a function or variable has access to other variables within the scope or the environment it was created in. They are sometimes used to emulate private methods. Which can only be called by other methods in the same class. Since JS does not have a native way of doing this.

Yes, one of the better explanations I've come across, too ... Concise, too ...

this is by far the best video - thanks

You get it simple, and you still get it well done.

Super helpful and straight to the point! Thanks a lot for sharing.

Thank you! I was really confused by closures.

Great explanation thanks!

Thanks, I have watched several great tutorial channels and yet, closure is still something i'm not confident talking about.

I logged in to say thank you. Gosh I finally understand what closures are. Wait, do I really???? lol

So just to make sure, in the second example there is no garbage collection on the environment the returned object is because that returned object references everything that is in it? How does this example compare to an ES6 class, or for the private part, classes on Typescript?

Just had a break through. Thank you.

It looks like a class emulation no ? You just instantiate an object called counter that has a property privateCounter and 3 methods in it.

Thanks for this, this helped give me a little more clarity with one of the lessons I'm learning in JavaScript on udemy. Liked and subscribed.

The only problem I notice with Beau's teaching method is that he goes from 20km/h to 150km/h in one second. If you try to play it at 0.75x, sometimes it will feel too slow, but if you play it at 1x, he speaks too fast 30% of the time.

Thanks for the example!

Clearly explained. Thanks!

Thanks for the example. It was an eye-opener. However, this appeared to reveal a bug in Firefox's JavaScript engine. The open curly bracket MUST be on the same line as the "return" statement. If one follows my bracketing convention, where the bracket is placed on the following line, the engine generates an error. However, if the object being returned is placed in a variable first, which is then returned, it works regardless of where the opening bracket is located.

Hi I am a little confused on how the privateCounter variable isn't getting destroyed and starting from 0 again every time counter is called, and is able to actually keep track of the count, as if it was a global variable. Is it that the variable counter is actually storing that information and doesn't destroy the values?

Thank you, that was an awesome explanation!!

Good tutorial about closure. thanks

Maybe you should tell people that whatever is in the closures will be stored there even many new lines away.

Thank you!

what is the use case of this?

Private methods in Java: private void printSomething() { System.out.println("I'm better"); } Private methods in JavaScript: This video

Great explanation of IIFS + Closures. /neededthat

still confused as all hell. you're glossing over subjects and not going over it thoroughly. GO MORE SLOWLY AND STEP BY STEP BY STEP BY STEP BY STEP. Amazes me how much CS skips steps when by nature it is all about logical steps

I finally understand!

This is some trick stuff. Thanks for the explanation though, its a bit more clear to me.

You are awesome!

So basically it's like a character in a sandbox game having access to all the stuff in their environment they exist within

that example is ripped straight from developer.mozilla.org/en-US/docs/Web/JavaScript/Closures :)

3:04 Access

this is complete mess explanation. ... That second attempt.

closures ? hard

would greatly appreciate if you talk louder instead of adjusting my speaker every time :(

coming from Java this behavior is quite odd, but ok, i guess xD

Uh. What!?

This is what I can NEVER understand and I never know why? I feel like I should better die.

ugh my brain hurts.

Dude...you cant use jargon with beginners. This was terrible

Mehn, JavaScript is hard...

Way too confusing of a presentation

I do understand closures (or at least I think I do) but that's a horrible explanation