Debouncing in Javascript | Flipkart UI Interview Question
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- Опубликовано: 8 фев 2019
- Debouncing is not just an important interview question, but it is also very useful to improve the performance of large scale web applications. A question based on this concept of Debouncing was asked to me while I was giving an interview at Flipkart.
Topics covered in the video :
1. Real-life scenarios using Debouncing to improve performance
2. Flipkart Interview Experience - question-based on concept of Debouncing in JS
3. Step by step approach of writing debounce function in the interview - Polyfill for debounce function
4. Code for implementing our own debounce function
Link to code - codepen.io/akshaymarch7/pen/w...
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Akshay Saini
akshaysaini.in
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Hi Akshay,
Because of your true efforts to learn and let others learn, i today got selected in amazon. Thanks a lot 🙏
Hearty Congratulations, Vishal. Keep shining! 😇
@@akshaymarch7 thanku akshay. Looking forward for more of your videos. U can even make videos on react. Would be awesome
@Vishal it would be great of you could let us know what Amazon expects from a front end engineer in interviews
@@vishalbisht6871 Hello Vishal can you Please tell how you have prepared and how you got the chance for the interview.
@@shivrajnag12 probably by studying in iit
Watching this at 2:03AM, feel like I learned something. Thanks Brother.
Watching this at 1:23 AM
Watching this at 1:03AM
Very good explanation @Akshay. However there are few bugs and unused variables in the code.
1. You haven't used 'fn' param in debounce function, though you have passed the 'argument' - 'getData' from 20th line.
2. If you had used the 'fn' param in the setTimout function, you would have avoided the getData function in line no.15
3. If you had adjusted the 2nd point right, you wouldn't need to keep the reference of 'this' and 'arg' unnecessarily, It would have automatically keeps the outer function params value intact. ( That's what closure does).
@@user-ht9eh7ex4v
```
let counter = 0;
const getData = function() {
console.log("Fetching Data...", ++counter);
}
const debounce = function(fn, delay=300) {
let timer;
return function () {
const context = this;
const args = arguments;
clearTimeout(timer);
timer = setTimeout(() => {
fn.apply(context, args);
}, delay);
};
};
const fetchDebouncedData = debounce(getData, 500);
fetchDebouncedData();
```
Hello sir, where does arguments come from in the function?
Was not getting debounce for so long, but you made it clear so easily...! Thanks mann!!
Hi brother I am watching your videos for some time now and in intial period I thought this is going to be like other channels with few tutorials of this and then few tutorials of that but I was wrong this is purely javascript based 100% pure content, I am Software Engineer in test at EA sports I can say the info you provide is legit, I use javascript everyday and use atleast 60% to 70% concepts you covered. Keep on doing this, we need more content creators like you. Stay motivated stay hungry
One of the best instructor . Thank you for your generosity.
Perfectly clear and concise. Thank you!
Never knew the term but was searching for this functionality to implement in an ongoing project!
Learned and implemented a new concept (checked) :-P
Thanks for this amazing video!
Haha same. Saw this video 2 years ago when I was preparing for interview and now I'm using this for a project at work. There is another way to do it but I will use this so I can learn something cool :D
Was using this concept since long, but now I get to know about it. Thanks man. Awesome video. Awesome explanation.
I am watching your video when my road is blocked from all side. This this the right place you will get right solution of your problem. Keep up the good work sir!
Learned the concept. Thank u very much. Will use in my existing and future development.
Sir! Your videos are really unique and great. Please keep posting more awesome core stuff like these.
Yeah, Awesome. Totally Practice and application.
Awesome... Was working on a search bar yesterday only... and the app feezed... Thank you introducing this concept.
Best thing learnt today. Found your channel today itself after seeing your post on LinkedIn. Your videos are really helpful. Thank you Akshay. 😊👍
I really start loving you and your effort :) Thanks man for such an easy to understand tutorials on JavaScript
Great tutorial Akshay.
Thanks for explaining and teaching the concept of debouncing in such an easy way.
GBY
Thank u sir 👊🏽 learnt a-lot from your content !!
after watching this video 4 times now i understand this concept ... :) thnks for this ....
Found your channel very late. But I'm glad I found it now 👍
recently i came across the videos of your channel and it has helped me to understand and getting mind set how to think of a solution for real project complex optimization. Keep publishing video with these simple easy to the point explanation.
thanks a lot. I just implement this concept in my project it makes a huge performance boost
If you are confused why timer variable need to defined outside of the anonymous function, that is closure !!!
Thanks , I learned something new today.
You are doing an awesome job akshay👍👍👍....I am using your videos as tutorials for preparing for interviews... the way you explain with examples and codes is really very helpful ... makes understanding the concept very easy... keep doing more such videos 👏👏👏
Thank you so much for this clear explanation. Thanks a lot.
Great conecpt, I'll be using it in my future developments.
simple way, deserved subscribe bro
Nice example Akshay but there are two things that are missing in the explanation one is timer variable which holds the setTimeout as closure and clearing out the setTimeout callback going to the event queue for event loop using clearTimeout function.
jab se maine Akshay bhaiya k namaste javascript video ko dekhna start kra exdm se love hone lga javascript mein.
Ab main kitne bhi hours javascript mein code kru mereko boring ni lgta.
Thankyou so much bhaiya for making these kinda videos.
very nice explanation agian :) 😅😅
Great explanation, it was really clear! Just want to point out a little thing that you forget to use the parameter fn (the function passed to debounce function) instead of directly use getData function in the body. Keep up the good work sir!
that good to point out any mistake as i also think same but as no comment is there for this mistake , i just think i am thinking it in wrong way.
Explained in such a simple way!
Thanks Man for this amazing content
Hi Akshay, thanks for better explanation. Please keep posting such type of new things that will help people's.
Thankyou so much for sharing these importing concept with very ease, it helping me in my skills and also in my interview.
Thank you so much, Akshay. You really doing very helpful job, explains every with such simplicity that even complex concept doesn't seems complex any more.
You're most welcome! 🙏
Now if I have encountered with any question from interviewer and don't know it, I come here to understand it. thanks Akshay
Explanation is so good... Loved and well understood.. Thanks lot
Please keep sharing.. its awesome content.
Now I can say I can implement debouncing anywhere needed😅. Thanks Akshay
Please keep making such enterprise level question videos along with solutions...u r doing great bro keep it up
This is something new to me. Thanks for sharing. 🙂
Thanks Akshay for making these videos.
Great informative video. Thanks
Bro. I not watched video and hearing audio only easy to understand that speaking. Smart learner to teaching easy way to know the concept... Smart move.. now I'm going to watch the video...🎉❤️
Hi Akshay,
You have explained dobouncing very well. Looking forward for more videos like this.
Released a related video today, this might help you - ruclips.net/video/81NGEXAaa3Y/видео.html
Very nice 👍
please come up with the more useful and hard topic of Javascript. Thanks a lot for Debouncing. it helps me.
Really cool concept bruh. Will write a article and will post your video in that .
Excellent explanation ..Thanks a lot
Akshay you have done a great job.
I can understand it would take more time behind the camera for making understand well. So keep it up this good job and helping us
Thanks @Akshay Saini For Awesome Explaination
Hi Saini, Lately I found your videos, Your videos helping a lot for me to understand the core concepts of Javascript. Thanka a lot.
This was awesome! Now i want to implement custom search bar in React with a database. 😂
Can you make a video on progressive image loading / lazy loading? How it is done effectively? I can find many implementations out there but confusing
God level clarity bro
Thanks dear Akshay! lots of respect!!!
Yesterday I couldn't answer this question in an interview and now m learning from your videos!
What company was that?
We want video on throttling!
Thanks Akshay😊 it was a nice demonstration on an important topic. Looking forward for more of these type of videos.
P.s. You're awesome!
Abracadabra, here it is - ruclips.net/video/81NGEXAaa3Y/видео.html
your explanation is superb thanks for making video on such topics
Hey aksay please make more videos on ecommerce design logic please
very nicely explained. keep it up.
bhaiya every video is new eye opener in itself!
I just love your videos brother you put all all your efforts in the explanation....I have found very few tutors who go that deep into the concept...love your work..🎉
Perfect explanation :)
Great explanation. Thx u!
Pls explain throttling and prototypes and prototypal inheritance and promises related interview questions. Also closures and currying and React js interview questions Akshay.
Videos for these topics are live now:
Throttling - ruclips.net/video/81NGEXAaa3Y/видео.html
Prototype & Prototypal Inheritance - ruclips.net/video/wstwjQ1yqWQ/видео.html
Hi Akshay, its really awesome work, you are doing. You explained debounce very nicely. Looks like, you missed to call fn() inside debounce method and instead you called the getData(). There is no impact on final output but since you are passing getData reference as first argument. So, it is better to call the fn(). Thanks Akshay keep doing this work. Friday night I started with one video of yours and i watched till 5 am morning. So, I have targeted to finish all your videos over the weekend. I feel like i am watching any online series. its to tempting and interesting. Thanks
I can see your comments regarding fn().
Thanks askay .. clearly understood
Great explanation, thanks.
Thanks for such video.
Got Great Concept !! Thanks !!!
I had used debouncing earlier but that was through lodash library ....Great Video :)
Yeah, it's best to use the loadash library if you're implementing debouncing in your webapp. But in interviews, it's frequently asked to write your own implementation of debounce function, just to check if the candidate understand what happens behind the scenes or not. 😊
@@akshaymarch7 Yeah I did implement first time in your video :P . Will definitely implement one in interviews if asked ;)
I added the code as a repo for those who would like to refer on Github. Here is the link : github.com/prateek951/js-interview-questions
Thanks Akshay :) . It's an awesome refresher.
@@TheNerdyDev Wow! that's awesome man. Thanks a lot for helping everyone. :)
Thanks a lot Akshay for amazing explanation on debounce. Requesting you to make similar videos on subject and behavioursubject.
Dude you are my fav person right now.. keep doing what you do man! Giving hope in these harsh times!
Thanks for this amazing video!
Glad you liked it!
Hi Akshay,
You are doing a great Job. Your videos are very useful.
I saw your videos of debouncing and throttling. They are awesome.
Can you please explain "requestAnimationFrame'' in your upcoming videos. Because this is also a way to improve the performance on UI.
Thanks a lot Akshay.
Minor correction:
At line 11 (timestamp- 7:54), it should be fn() and not getData()
thanks a lot..very nice explaination
Hi Akshay,
Correct me if I am wrong.
In this case, there is no need to bind the getData function like getData.apply(context) where context is pointing to "this'".
debounce function is in the global scope. so "this" inside it is pointing to global i.e window object;
"this" keyword in the anonymous function that is inside the debounce function point to the input field.
And finally, since function inside the set timeout is an arrow function, "this" inside it will automatically take its reference from its enclosing scope that is an outer anonymous function.
So "this" inside arrow function point to input field.
But since getData() function called without "this" keyword so it automatically points to the global scope where getData() function is defined.
Subscribed.. due to this video's content.
Keep doing good work Akshay.
Thanks & regards
Your LinkedIn Connection🙂
Awesome.. Well explained.
Thank You. nice knowledge share.
Throttling is better way to handle than debouncing, as always last current data is sent after every throttle period. In any case, both approach still does not know how to clear last call already made to server (assumption is even server may take x time at server to service each call). It is important even server to drop obsolete call if respective next relevant request has come..
Hi Raja, Thanks for recognising the efforts.
However to add to your point, I won't agree that throttling is a better way than debouncing. They are altogether very different and we can't compare between them. But I've personally find myself stuck in many situations were debouncing helped me instead throttling. Thanks :)
Great work . Good going
Awesome explanations !
Is there any way , where instead of passing delay time we can detect when keyStroke event has stopped ?
0:00 Intro
1:14 Context/Recap
2:58 Code init
12:26 Code complete & test
13:40 Refactor & Conclusion
Hi Akshay,
What will happen, if function inside setTimeout takes more time to complete the execution than the delay time. Is there any impact on application.
Hi Akshay, how debouncing is different from throttling? In throttling video you showed similar example for delaying the event using flag instead of timer.
very nice way you explained
hey, thank you for the video. One question here regarding the context in setTimeout? Is that really required? It will be pointing to window always right?
Hi Akshay,
First a fall quite a nice explanation looking forward for more content
If could made a video on namedropping and how to break js code into different module (use of require)and ways as well
It would be great help If you could also explain how they loaded if target to single file to execute
Crystal clear bro. Thank you bro.
You are champ brother!!!
question: why don't we just use debounce(getData, 300) IN the event callback? I tested this and works also. Why do we go the extra step of returning the function into another variable (betterFunction) and passing that as the event callback?
Hey dee. Which method did u call in html keyup?I also did try this. But won't work
@@alradiation5417
let debounce = function(originalFunction, delay){
let timer;
return function (){
clearTimeout(timer);
timer = setTimeout(() => {
originalFunction();
}, delay);
};
}
let fetchData = function(){
console.log("fetching data");
}
const INPUT = document.querySelector("input");
INPUT.addEventListener("keyup", debounce(fetchData, 300));
So how will you pass in parameters for this function, that's why we use apply method
thank you so much akshey vai
Hi Akshay,
First of all thankyou so much for sharing this beautiful concepts with us. I am really liking your all sessions😇. I just have a request , could you please explain about indexdb also
I have nicely understood the concept of debouncing method except that `apply( )` and `context`. Can you please suggest any link for context and apply method ?.
Very nice explanation 👌✨🎉
Hey It is an amazing video to learn on debouncing. Thanks a lot
Can you please help me to get why he take
let context = this ,
Argu=arguments
Thanks for your video! love it. One typo: line#15 should be 'arg' instead of 'arguments'.
Thank you Akshay...
Awesome 👍
Awesome Work Akshay!
Very useful. 👌