Closure is often confused with Lexical Scope. Lexical Scope is an important part of closure, but it is not closure by itself. This tutorial provides several examples that should allow you to distinguish between lexical scope and closure. This tutorial should also allow you to learn how to give examples of closure if you are asked during the interview process. It is important to understand scope when we discuss closure. If you need to learn more about scope, check out my scope tutorial here: th-cam.com/video/_E96W6ivHng/w-d-xo.html
Hi! Supposing you have some secret JavaScript functions that you don't want anyone to know. Also, that code (functions) are very resource consuming and this is why they need to be client side and not server side so you can't write those functions in python or php. Also, obfuscation of JavaScript is not useful since it can be easily deobfuscated or seen by placing a breakpoint in the debugging tools in the browser. This been said, could you make, please, a tutorial teaching us the best way to protect your secret JavaScript functions without paying for third party services? Thank you so much in advance!
Out of all the yt tutorials on closures I've watched today, this one's been by far the best. Clearly explained step-by-step with readable code as illustration. Calm voice, proper English pronunciation and slow pace of speaking matter particularly to beginners like me. Unlike most teacher-coders on yt, you're actually capable of teaching. Thank you, good job, I'm going to watch more of your tutorials.
Thank you, Dave! An extremely complex concept was explained clearly. Finally, I understood what closure is and how to use it in my code. The IIFE was a cherry on top. Thank you again.
I can't tell you how much I appreciate the pace of your speaking voice when explaining these concepts. So many of these youtube videos, the person is talking insanely fast, and I cannot keep up with all of it.
I discovered you today, Dave and I am highly impressed with your teaching style. Unlike many other YT videos that teach all this stuff, I can actually understand you. (So many are hard to follow due to the thick accent of the instructor.) I'm looking forward to delving into other videos you have. Thank you!
This is the first video I've come across, so far, that really goes deep into clearly explaining that simply having an inner function and logging its parents' variables isn't a closure but a lexical scope. Brilliant!
I was writing closure example after example without really understanding the reason behind it and this video with credit example finally got the closure idea to click. Thank You.
Just learned closure several days ago. This video definitely helped me review the concept. It also helped me clear up the confusion about lexical scope. Thanks Dave!
this is an underrated tutorial, i had to got to the bottom of the page on the youtube to get this video. these explanations & examples are more than enough to understand what closure is.
The majority of videos made by other content educational creators across various websites talk like they're rappers, you sir are different. Things went much clearer after this video and made me realize that the majority of my confusion is because most of my searches were actually lexical scopes and not closures. I really am indebted to you.
Just a quick thought. I think the "credits =- 1" line should be at the end of the function since we need to check credits' amount first to evaluate the possibility of playing. In the example we should be able to play 3 times and it only allows two plays. Everything aside, great video and I always find your explanations very helpful!
Before coming across your video I had already watched three other ones that weren't explanatory enough for me. Thank you so much for this video; I got everything. Thank you.
Thank you very much, Dave. You explained it in a very beautiful way possible. You know I had been struggling from this since long. There wasn't any such explanation on the internet! Thanks a lot.
Great video! This explains a lot and you've got a new subscriber. It might be my lack of Javascript knowledge but I still don't quite understand why after the first time, every time the parent function is called, only the child function executes and not the WHOLE parent function. I'm going to watch it a few more times and see if it sinks in. Thanks for the video!
Glad it was helpful! This explanation may help... The parent function is only called once. It returns the "child" function. The variable is therefore set to the child function that is returned. Afterwards, using the variable, only the child function is called. The closure allows the child function to still access the variable that was created within the parent. What we're really referring to here is the lexical scope of the function that is returned, but using the parent and child terminology could help! 😀🚀
I have smashed that like button and I hope that this playlist keeps growing as these concepts really make a difference. Thank you for sharing your knowledge with us
Dave, you need to seriously consider putting together a Javascript course with projects for Udemy. Your explanations are crystal clear. I have found myself doing course after course, stopping, and then trying to find someone else who would be able to explain the concept a bit clearer than the instructor. It wastes a lot of time. I have found myself coming here for the past three or so concepts, and they click straight away. So thank you.
Thanks man, I've been struggling with this for days! This video finally made me understand closures (it gave me the aha! moment). I liked the way your video went beyond the cliche closure examples which weren't allowing me to actually understand practical uses for closures. Subscribed!
Thank you for your video! This is the most understandable explanation of closures I've seen and has solidified my understanding of the concept. Really appreciate the emphasis on what "lexical scope" is and how it's an integral part of -- but not the whole story with -- closures. Truly awesome! Thank you, good sir!
Hi DaveGray, I’m a student and have completed learning the MERN stack from your channel. I would love to see a course focused on building microservices with serverless architecture. It would be great if you could cover topics like designing, deploying, and scaling microservices using platforms such as AWS Lambda please.
Dave, thank you so much for this tutorial. I finally got my "Gotchaa!" moment about closures. I watched several explanations before but this really helped me to understand. Lifesaver :)
Thanks for all you do, Dave. Your videos are the best. I've watched several videos on closures, but none of them explained it better than you did. I finally understand closures!
Dave, thank you so much for your tutorials! All of them are very well structured and easy to understand. I really appreciate all the work you do. Thanks again. Awesome channel! 💛
In the beginning, I found it difficult to understand the topic "closures" it is so confusing. After watching your video demo, I understood it. Thank you very much Dave.
I wish I had stumbled across your video sooner! I've been trying to wrap my brain around closures for so long. Super helpful! You got a new subscriber!
I "Thumbs Upped" your video. I've been studying JS recently for a few months, and to my surprise everything is getting easier to understand, like I'm on the steeper part of the learning curve. I've been getting a clearer picture of what closures are, but your explanation helped even more to demystify closures to me. You have a very sensible, logically explanatory and intelligent way of explaining closures. I'll be checking out your other videos because I like your teaching style. Who knows, maybe I'll buy you a cup of coffee :).
Hello Dave. Your contents are tremendously helpful to me as a self-directed learner of frontend dev. You've got yourself a new subscriber :). Your explanation of JS closure is crystal clear but I still have a burning question which I hope your could provide clarification. I am tempted to say the reason that nested function still have access to outer function's variable, even after outer function has returned, is that garbage collection can't destroy these variable. They are still referenced by a nested function. In other words, these variables are still present even though the scope in which they were created is not. Thanks again for your time and efforts!
12:45 The important highlight he mentions. IIFE code happens once. The anonymous function inside it only get's returned ONE time (to privateCounter). After that, you can look at privateCounter as: privateCounter = () => { count +=1; console.log(count) } //but with it's own access to private variable "count". -I'm guessing you can say it has enClosed it's scope over the function and it's declared variables. 5:45
I've been programming on JavaScript for over 2 years, I hope I'll feel ready to apply for a job soon, even being old to start, I'm 36. Until now, if I was asked about Closure I replied about lexical scope. The IIFE explanation was interesting although I knew it already, because I used them on my API. I do full stack with MERN. Anyway, great video, very clear explanation. 👏👏👏
This video was an instant subscribe. It was well thought out and clear, and I now understand two concepts much better than ever before. Closure kind of blew my mind. Thank you so much for sharing your knowledge!
Really loved the ball field analogy! At times I’ve struggled to explain the concept of closures to teammates. this will help greatly… thanks for the great content!
Very good explanation. I think what I really wanted to see by the use of closures was the outer function returning an object consisting of functions. This gives you the ability to isolate your data similar to how classes work.
Awesome. Pretty common concept coming from Laravel, PHP (we call it "a function called from another function"). That made me familiar to the concept beforehand. But I was lost on the application in JavaScript. Amazing, top-notch explanation, Dave! Now, I can use it in JS.
Dave, this was really excellently explained. It finally clicked for me. However, like most videos on this subject, I feel like a critical piece of information is missing. The why? So a closure allows me to hide (encapsulate) a function's local variable. Why would we want to do that?
Thank you! Closure is used in many places once you recognize it. For example, it is used all the time in React. For Vanilla JS, here are a couple of tutorials that use it: 1) Debounce functions: th-cam.com/video/yBFHwJgqLD4/w-d-xo.html and 2) Memoization: th-cam.com/video/TWUV_LRVX24/w-d-xo.html
Thank you for an excellent learning experience! By far the best explanation of what initially appears to be a difficult concept. Subscribing so that I can actually learn to understand things from an excellent teacher!
I'd be happy to also see some closure pitfalls examples. closures are not that useful to know without pitfalls in my opinion. It's just something that you expect to work. however pitfalls show that sometimes closures are against you!
Closure is often confused with Lexical Scope. Lexical Scope is an important part of closure, but it is not closure by itself. This tutorial provides several examples that should allow you to distinguish between lexical scope and closure. This tutorial should also allow you to learn how to give examples of closure if you are asked during the interview process. It is important to understand scope when we discuss closure. If you need to learn more about scope, check out my scope tutorial here: th-cam.com/video/_E96W6ivHng/w-d-xo.html
Thank you Dave ❤️
Thank you for another great video Dave!
@@YuRiSsS you're welcome! 🙏
@Abhijit Desaithank you! That's a great request 💯 I like that idea.
Hi!
Supposing you have some secret JavaScript functions that you don't want anyone to know. Also, that code (functions) are very resource consuming and this is why they need to be client side and not server side so you can't write those functions in python or php.
Also, obfuscation of JavaScript is not useful since it can be easily deobfuscated or seen by placing a breakpoint in the debugging tools in the browser.
This been said, could you make, please, a tutorial teaching us the best way to protect your secret JavaScript functions without paying for third party services?
Thank you so much in advance!
Out of all the yt tutorials on closures I've watched today, this one's been by far the best. Clearly explained step-by-step with readable code as illustration. Calm voice, proper English pronunciation and slow pace of speaking matter particularly to beginners like me. Unlike most teacher-coders on yt, you're actually capable of teaching. Thank you, good job, I'm going to watch more of your tutorials.
Glad I could help, and thank you! 🙏💯
Thank you, Dave! An extremely complex concept was explained clearly. Finally, I understood what closure is and how to use it in my code. The IIFE was a cherry on top. Thank you again.
Glad to hear it and you're welcome! 💯
Dave grey taught me html and css! Now he's teaching me one of the javascript topics I find hard to understand! I love this guy, he's the best!!
You have a laid back, natural, and clear way of explaining things. Much appreciated!
Thank you for the kind words! 🙏🙏
I spent the whole day looking up videos to understand closure, and finally I could find the best one. Thank you so much.
Thank you so much for the kind words! 🙏💯
You explained closures in a way that even a primary school student will understand. You definitely deserve a sub. Thank You so much, Dave!
You're welcome!
I has started learning web dev from your html videos ...last april .. thanx for teaching us and making begginer understand the relevant topics....
I can't tell you how much I appreciate the pace of your speaking voice when explaining these concepts. So many of these youtube videos, the person is talking insanely fast, and I cannot keep up with all of it.
I'm glad it helps! 💯 If anyone wants it faster, TH-cam lets them speed it up 😀
I spent the whole day looking up videos to understand closure. finally i git it so Thank you so much for clearly and simply explaining
I discovered you today, Dave and I am highly impressed with your teaching style. Unlike many other YT videos that teach all this stuff, I can actually understand you. (So many are hard to follow due to the thick accent of the instructor.) I'm looking forward to delving into other videos you have. Thank you!
This is the first video I've come across, so far, that really goes deep into clearly explaining that simply having an inner function and logging its parents' variables isn't a closure but a lexical scope. Brilliant!
Glad it was helpful!
I was writing closure example after example without really understanding the reason behind it and this video with credit example finally got the closure idea to click. Thank You.
Glad to hear it helped!
Just learned closure several days ago. This video definitely helped me review the concept. It also helped me clear up the confusion about lexical scope. Thanks Dave!
You're welcome! 💯
Finally I fully understood closure.... thank you and bless you
this is an underrated tutorial, i had to got to the bottom of the page on the youtube to get this video. these explanations & examples are more than enough to understand what closure is.
Glad it helped!
i watched too many closure videos but first time i understand clearly . thank you so much
Glad it helped! 💯
Great! Great! Great! Thank you very much! Very good explanation! Very good examples!
You are welcome!
The majority of videos made by other content educational creators across various websites talk like they're rappers, you sir are different. Things went much clearer after this video and made me realize that the majority of my confusion is because most of my searches were actually lexical scopes and not closures.
I really am indebted to you.
You're welcome!
Just a quick thought.
I think the "credits =- 1" line should be at the end of the function since we need to check credits' amount first to evaluate the possibility of playing. In the example we should be able to play 3 times and it only allows two plays.
Everything aside, great video and I always find your explanations very helpful!
Best video tutorial on javascript closures on the whole internet.
Period!
Thank you!
This is by far the best tutorial on closures I've watched. Thank you!
Glad it was helpful!
The best and detailed "Closure" explanation on the internet
Thank you! 🙏🚀
your last example was lovely , thank you
Glad you liked it!
Before coming across your video I had already watched three other ones that weren't explanatory enough for me. Thank you so much for this video; I got everything. Thank you.
You're welcome! 💯
Thank you very much, Dave. You explained it in a very beautiful way possible. You know I had been struggling from this since long. There wasn't any such explanation on the internet! Thanks a lot.
You're welcome, Umair 🙏
Great video! This explains a lot and you've got a new subscriber. It might be my lack of Javascript knowledge but I still don't quite understand why after the first time, every time the parent function is called, only the child function executes and not the WHOLE parent function. I'm going to watch it a few more times and see if it sinks in. Thanks for the video!
Glad it was helpful! This explanation may help... The parent function is only called once. It returns the "child" function. The variable is therefore set to the child function that is returned. Afterwards, using the variable, only the child function is called. The closure allows the child function to still access the variable that was created within the parent. What we're really referring to here is the lexical scope of the function that is returned, but using the parent and child terminology could help! 😀🚀
Wow that quick explanation really helped. Thx
Thanks Dave you could help me to understand the most confusing concept in js, after I read a lot of articles and watched a ton of tutorials.
You're welcome! Glad I could help. 💯
I have smashed that like button and I hope that this playlist keeps growing as these concepts really make a difference. Thank you for sharing your knowledge with us
You're welcome! Glad I could help 💯
I really found this explanation about lexical scope and closure the best one from TH-cam. Thank you.
Glad it was helpful! 💯
Dave, you need to seriously consider putting together a Javascript course with projects for Udemy. Your explanations are crystal clear. I have found myself doing course after course, stopping, and then trying to find someone else who would be able to explain the concept a bit clearer than the instructor. It wastes a lot of time. I have found myself coming here for the past three or so concepts, and they click straight away. So thank you.
Thank you, Darryl! I do hope to put a premium course together sometime later this year. I am not sure if Udemy is where I will launch it though.
Thank you for clarifying IIFE, it's syntax that has been tripping me up and now I understand what it's doing. Excellent demonstrations for closures.
Thank you, Wallace. 🙏
I watched maybe 10 videos on closure. Finally one person can explain it well, Dave Gray! You also crushed on that song white ladder.
Ha! I do share my name with a few others, but I'm glad I could help with closures! 💯🚀
Thanks dude, it's so clear. I will definitely rewatch this over and over again until I am very familiar with the concept.
Your tutorials are simply the best on TH-cam, thanks for your effort you put for creation high quality content for free ! ❤
This is what closure is...I was just thinking lexical scope is closure. Superbly explained. Thanks alot.
You are welcome, Tushar! 🙏
Thanks man, I've been struggling with this for days! This video finally made me understand closures (it gave me the aha! moment).
I liked the way your video went beyond the cliche closure examples which weren't allowing me to actually understand practical uses for closures.
Subscribed!
Thanks again, John - check out my tutorials on debounce, throttle, and memoize to see closures put to good use, too. 🚀
Thank you for your video! This is the most understandable explanation of closures I've seen and has solidified my understanding of the concept. Really appreciate the emphasis on what "lexical scope" is and how it's an integral part of -- but not the whole story with -- closures. Truly awesome! Thank you, good sir!
Thank you so much for clearly and simply explaining this concept!
You're welcome, Stephanie!
Thanks Dave for this video, please continue the advanced js playlist. You explaining hard concepts easy to understand.
You're welcome, Shiva! I do plan to do more 🚀🙏
The best teacher to explain advanced concepts of Javascript. Instant subscription!
Welcome aboard! 💯🚀
Finally , finally I could wrap my head around this concept. It's so basic and easy.
Glad I could help! 💯
Excellent explanation, thank very much for this video!
Thank you Dave, you just got a new subscriber
Clear, simple, concise, well spoken and very useful. I followed along with your code in my IDE (Velo) with no difficulty. Thank you.
Great to hear!
Probably the best Closures video I have ever watched. Thanks!!
Glad you liked it!
Hi DaveGray,
I’m a student and have completed learning the MERN stack from your channel. I would love to see a course focused on building microservices with serverless architecture. It would be great if you could cover topics like designing, deploying, and scaling microservices using platforms such as AWS Lambda please.
Dave, thank you so much for this tutorial. I finally got my "Gotchaa!" moment about closures. I watched several explanations before but this really helped me to understand. Lifesaver :)
Glad it helped!
People misunderstand js a lot. People like u make it relevant for us js peeps. Keep going!
Thank you!
Thank you for clear examples, I finally understood. I looked at other youtubers and it was confusing.
Glad it was helpful! 💯
Thanks for all you do, Dave. Your videos are the best. I've watched several videos on closures, but none of them explained it better than you did. I finally understand closures!
Awesome, thank you!
Dave, thank you so much for your tutorials! All of them are very well structured and easy to understand. I really appreciate all the work you do. Thanks again. Awesome channel! 💛
You're welcome!
In the beginning, I found it difficult to understand the topic "closures" it is so confusing. After watching your video demo, I understood it. Thank you very much Dave.
Glad it was helpful! 💯
This is by far the best explanation of JS closure. Thank you Dave. I'm glad I came across your channel.
Glad it was helpful!
This was a great video. I was struggling with closures for some days but now I feel like i understand it now. THANKS Again it was a great video.
Thank you, Kumari. Glad I could help!
Perfectly perfectly and perfectly explained. Congrats
Not bored at all. Nicely presented. :)
Thank you! 🙏
I wish I had stumbled across your video sooner! I've been trying to wrap my brain around closures for so long. Super helpful! You got a new subscriber!
Thank you, Beth!
This is the only explanation that made me understand it, thank you
this man, helps me to understand closure quickly and easily!
Glad to hear it! 🚀
well chosen examples demonstring the unique characteristics of closure. Finally undertand it now!
I "Thumbs Upped" your video. I've been studying JS recently for a few months, and to my surprise everything is getting easier to understand, like I'm on the steeper part of the learning curve. I've been getting a clearer picture of what closures are, but your explanation helped even more to demystify closures to me. You have a very sensible, logically explanatory and intelligent way of explaining closures. I'll be checking out your other videos because I like your teaching style. Who knows, maybe I'll buy you a cup of coffee :).
Thank you for the kind words 🙏💯
This is the best closure explanation for me... Great work.
Glad it was helpful! 💯🚀
Hello Dave. Your contents are tremendously helpful to me as a self-directed learner of frontend dev. You've got yourself a new subscriber :). Your explanation of JS closure is crystal clear but I still have a burning question which I hope your could provide clarification. I am tempted to say the reason that nested function still have access to outer function's variable, even after outer function has returned, is that garbage collection can't destroy these variable. They are still referenced by a nested function. In other words, these variables are still present even though the scope in which they were created is not. Thanks again for your time and efforts!
You're welcome! Good comment, too. I believe you can say the lexical scope of the function still exists because the function exists. 🚀💯
Concisely put!
Nice video 🎉. I think the definition would be when a function returns another function that is defined inside the function is a closure function!
Best video about closure so far. You are a very good teacher.
Thank you, Ren! 🙏
It’s so refreshing to listen,well explained.Thank you Dave
You are very welcome
This is the best tutorial on Closures.
Thank You!
Glad it was helpful!
finally found a video about closures that makes sense. Thanks
Glad it helped!
12:45 The important highlight he mentions.
IIFE code happens once. The anonymous function inside it only get's returned ONE time (to privateCounter). After that, you can look at privateCounter as:
privateCounter = () => { count +=1; console.log(count) } //but with it's own access to private variable "count".
-I'm guessing you can say it has enClosed it's scope over the function and it's declared variables. 5:45
Thank you, I really thought that I know closures, but I was completely wrong, nice video
Happy to help!
Replayed this video several times. I think i now get it finally 😂. W3 definition makes alot of sense now.
Right on! 🚀
I've been programming on JavaScript for over 2 years, I hope I'll feel ready to apply for a job soon, even being old to start, I'm 36. Until now, if I was asked about Closure I replied about lexical scope. The IIFE explanation was interesting although I knew it already, because I used them on my API. I do full stack with MERN. Anyway, great video, very clear explanation. 👏👏👏
Thank you, Leonardo 🙏 You're never too old to do what you love - keep making progress! 💯
One of the best video on closure
This was a masterclass on how to explain abstract concepts with easy-to-follow, real-world examples. Thank you. Subbed!
Awesome, thank you!
Finally I understood JS closures!
Subscribed!
Glad to hear that!
This tutorial is so well structured it simplified the closure concept in a brilliant way!! Thanks a lot
You're welcome! 💯
This video was an instant subscribe. It was well thought out and clear, and I now understand two concepts much better than ever before. Closure kind of blew my mind. Thank you so much for sharing your knowledge!
Welcome aboard! And glad it was helpful!
Really loved the ball field analogy! At times I’ve struggled to explain the concept of closures to teammates. this will help greatly… thanks for the great content!
Glad it was helpful!
Very good explanation. I think what I really wanted to see by the use of closures was the outer function returning an object consisting of functions. This gives you the ability to isolate your data similar to how classes work.
Thank you! You describe a nice advanced example! 💯🚀
Thank you so muchhhh
The best closure explanation ever
Your videos are absolute gems 💎. Keep up the good work.
Thank you! 🙏
How did I now know about this channel before. Thank you.
You're welcome!
Excellent ! I was struggling to understand dynamic between Closure and Lexical Scope.
Glad I could help, Alex! 💯
Good explanation, thank you sir :)
Welcome!
I just reviewed this. You could do a related one on Crockford objects - avoiding classes.
Best explaination on the web. Great job sir! Thank you!
Thanks had problems with understanding Closure... wish my prof. could do as good of a job explaining thing like you do
Thank you for the kind words, Bashar! 🙏🙏
Clean explanation, thank you ! Very powerful but... miserable to debug !??
You made closure clear to me! Thank you so much!
Glad it helped!
just found out about this series! Loving them
Thank you, Chetan! Glad you like it! 💯
Good Job Dave people like you who make instructional videos are milestones for your knowledge
Thank you for the kind words, Kaan. 🙏💯
Thank you ! The explanation is extremely clear for beginners.
Glad it was helpful! And you're welcome! 💯
Awesome. Pretty common concept coming from Laravel, PHP (we call it "a function called from another function"). That made me familiar to the concept beforehand. But I was lost on the application in JavaScript.
Amazing, top-notch explanation, Dave!
Now, I can use it in JS.
Glad you liked it!
Dave, this was really excellently explained. It finally clicked for me. However, like most videos on this subject, I feel like a critical piece of information is missing. The why? So a closure allows me to hide (encapsulate) a function's local variable. Why would we want to do that?
Thank you! Closure is used in many places once you recognize it. For example, it is used all the time in React. For Vanilla JS, here are a couple of tutorials that use it: 1) Debounce functions: th-cam.com/video/yBFHwJgqLD4/w-d-xo.html and 2) Memoization: th-cam.com/video/TWUV_LRVX24/w-d-xo.html
Thank you for an excellent learning experience! By far the best explanation of what initially appears to be a difficult concept. Subscribing so that I can actually learn to understand things from an excellent teacher!
dang, that was the best closure tutorial that I've ever seen
Thank you, Yuri! 🙏💯
Thank you so much , for this explanation i was so confused about closure
Glad it was helpful!
I'd be happy to also see some closure pitfalls examples. closures are not that useful to know without pitfalls in my opinion. It's just something that you expect to work. however pitfalls show that sometimes closures are against you!
Brilliant explanation IIFE , my friend.Thanks
Glad it was helpful! 💯