Promises | Ep 02 Season 02 - Namaste JavaScript
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- เผยแพร่เมื่อ 4 ก.ค. 2024
- Promises is the new way of handling asynchronous operations in JavaScript. This episode of Namaste JavaScript Season 2 will explain how Promises work in JavaScript along with code examples in detail.
00:00 - Introduction
00:50 - Code Example of Callbacks and Promises
08:05 - Promise.then function
09:30 - Callbacks vs Promises
11:23 - Importance of Promises
12:22 - Promise Object in Browser
15:58 - Deep dive into Promise States
21: 52 - Promise Interview Question
25:20 - Promise Chaining in JavaScript
30:13 - Common mistake while Promise Chaining
33:17 - Recap of the video
36:22 - Teaser of the Next Video
37:11 - Homework of this episode
38:32 - Thank you for watching Namaste JavaScript 🙏
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Your teaching will have a huge impact in the world. I'm grateful for the time and energy that you put in to make such complex Javascript concepts simple. Thank you 🙏
Thank you so much for supporting my channel. This means a lot. ❤️
currently I am pursuing mca from ignou (open) and before that I have done bsc mathematics .I am fresher .I wants to work at top companies.many of friends are telling with these degrees I cant join top mnc as they dont give preference to open degree .I am very much frustrated .is it TRUE?
@@ayushi8412 Ayushi actually your degree doesn't matter I myself is currently doing BCA and will do MCA in the future and I also have heard these opinions of people that you won't get a job if you're doing MCA or having a open degree but what I have seen and learned is that in today's world the top companies seeks skills over degree soo if you have really good skills then you will definitely get a job in top companies, Hope this helps :)
@@ayushi8412 No
@@prathamjaiswal1082 I have done the MCA and I don't think it made any difference in my career. I would have grown my career for 3 more years if I had searched for a job after BCA and might have become a team leader today. not a single interviewer asked about my MCA academics
1. Before promise we used to depend on callback functions which would result in 1.) Callback Hell (Pyramid of doom) | 2.) Inversion of control
2. Inversion of control is overcome by using promise.
2.1) A promise is an object that represents eventual completion/failure of an asynchronous operation.
2.2) A promise has 3 states: pending | fulfilled | rejected.
2.3) As soon as promise is fulfilled/rejected => It updates the empty object which is assigned undefined in pending state.
2.4) A promise resolves only once and it is immutable.
2.5) Using .then() we can control when we call the cb(callback) function.
3. To avoid callback hell (Pyramid of doom) => We use promise chaining. This way our code expands vertically instead of horizontally. Chaining is done using '.then()'
4. A very common mistake that developers do is not returning a value during chaining of promises. Always remember to return a value. This returned value will be used by the next .then()
Great share ❤
ok
aani
@@niharikakesarwani8290 ok
This is so helpful, thank you.
Lovely Explanation
1. A promise is an object that represents the eventual completion or failure of an async operation.
2. A promise is helpful in dealing with callback hell and inversion of control. Promise chaining helps in making the code more readable and maintainable.
Before promise we used to depend on callback functions which have two disadvantages
1.) Callback Hell (Pyramid of doom)
2.) Inversion of control
1) Inversion of control is overcome by using promise
promise is object represent the eventual completion of asynchonous operation
a)A promise has 3 states: pending | fulfilled | rejected.
b) As soon as promise is fulfilled/rejected => It updates the empty object which is assigned undefined in pending state.
c) A promise resolves only once and it is immutable in nature.
d) Using .then() we can attached the cb(callback) function.
2) - To avoid callback hell (Pyramid of doom) => We use promise chaining. This way our code expands vertically instead of horizontally. Chaining is done using '.then()'
- A very common mistake that developers do is not returning a value during chaining of promises. Always remember to return a value. This returned value will be used by the next .then()
Watch Next Episode - th-cam.com/video/U74BJcr8NeQ/w-d-xo.html
This Episode is a little long, but trust me everything taught is super important. Watch this video with full attention and also finish the homework given at the end of this video. All the Best. Keep Rising! 🚀
bro thanks a lot.....lots of love.....❤❤❤❤❤❤❤❤
Bro we can bear with you even 1hr long...You never disappoints us🙂
It was really amazing as previous videos. One of the best explanation on TH-cam.
Hello Akshay Sir, your explanation is very great and very useful, I am fresher in javascript and I want to learn javascript can you tell me how to start?
- What is promise?
Promise is an object, which represents eventual completion of async operation.
- Why promises are important?
promises are important because
1. Promises guarantee you that callback functions are called whenever they have response with them.
Javascript guarantees you that callback functions are called 100%.
2. Promises guarantee you that callbacks are called once.
So like traditional callbacks these are not called multiple times or not at all.
3. It provides us full control of code, so we don't need to handover or depend on external function.
1. What are Promises?
Promises are objects which are used to perform asynchronous operations. They are just like placeholders to store a future value that will be returned after some time. They contain two properties: PromiseState and PromiseResult.
2. Importance of Promises:
a) Promises can help us to write trust worthy code.
b) Promises are used to solve the problems of callbacks like inversion of control and callback hell.
c) They give us the result prompt in three states: 1) Pending 2) Fulfilled 3) Rejected
d) We can attach function to promise object and retrieve its value unlike callbacks no need to pass the function.
e) Nesting can be done in Promises and with the help of that we can return the values in each individual chain.
Thank you bhaiya, for this awesome explanation of Promises.
You might add to list -> promise result is immutable
currently I am pursuing mca from ignou (open) and before that I have done bsc mathematics .I am fresher .I wants to work at top companies.many of friends are telling with these degrees I cant join top mnc as they dont give preference to open degree .I am very much frustrated .is it TRUE?
@@ayushi8412 If you can master CS topics like DSA, DBMS or OS then you can still apply to top MNC's
@@ayushi8412 hii what are you doing now?
A Promise is an object which represents eventual completion or failure of an asynchronous operation. Promises are immutable once resolved and they give us a lot of control over our code. They have three state pending, fulfilled or rejected. The promise object contains two parts 1) PromiseState(stores the sate of the prmise) and 2)PromiseResult(stores data)
1) A Promise is an object that represents the eventual completion or failure of an asynchronous operations.
2) Importance of promise is that we do not loose the control of the program, a promise object is immutable and can be send anywhere without worrying about changes, also it resolves only once either to success or failure.
Length is not at all a issue, rather it's a blessing it means the video is loaded with lot of awesome content. Thank you so much for all your efforts
♥️
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if you know which font family use in this video plz send reply
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#masai
Love the way you explain the topics with so much passion. Grateful for your videos 🙏🙏
Thank you so much for supporting my channel, Kamalendu. This means a lot. ❤️
I like the definition that it’s a placeholder for an asynchronous operation. I like that you are focusing on what to say in an interview because that is why I am watching these videos for review of many things
A promise is an object, which represents that, mentioned Asynchronous operation will eventually be completed.
Thanks Akshay for the courses which promise us to make our life much easier❤❤
Thanks! Your videos are helpful in understanding and loving javascript and in career. A small contribution from my side for your huge efforts.
Thank you so much for supporting my channel. This means a lot. ❤️
aur 900 rupe kero fir pin hoga tumhara comment
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Promise is an object that represents the eventual completion of an asynchronous operation.
Promises are immutable so it can't be altered as a result it helps to get rid off inversion of control that would be occurred in case callback and by chaining of promises we can get out of the callback hell.
In chaining of promises we should use return to get the promise result so that we don't miss anything from the chain.
Thank you sir for your efforts it's just like charity (good deeds ) and God will bless you for this selflessness.
Every time I have problem in JS, I come to this channel and If I find it in namaste video title I know that after watching it I will have 100% understanding of the subject which won't be a problem anymore. Thanks a lot
Promises is an object that represents the eventually completion or failure of an asynchronous operations.
Disadvantage of callback
- Callback Hell (Pyramid of DOOM)
- Inversion of Control (Lost the control over the code)
We overcome the Inversion of control by using promises,
You are amazing teacher and explained complex things in beautiful / simple way. Thank you so much🙏
Before watching this video, my state for concept promise was PENDING, but now I can definitely say its much better than RESOLVED 😄
Hats off for detailed discussion, it was a GEM.
Heyy Akshay.
As much as the content is presented so beautifully, the excitement with which you explain the stuff shows how much you love Javascript and how much you love teaching it.
There's always so much to learn from you, and that's not just Javascript. Great job!!
Well explained. Just saw your first video and I am blown away by the way you have dig in deep to explain every single detail. Looking forward to check out more of your videos
God wants this guy to teach people. Greetings from Russia❤
I am a civil engineer. I searched and purchased so many courses but none of them taught me the way you did. Thank you for making my transition to this field so smooth.
That thumbnail, that eagerness to teach, that content, everything is awesome 🔥. You are literally a god in JavaScript teaching 🙏
Thank you so much! Couldn’t find any other video that could explain promises better 🙏🏻
Promise is an object that represents eventual completion or failure of an asynchronous event.
Advantages of promise are:
1. Promise eliminates the problem of Inversion of Control as in case of call backs.
2. Promises brings lot of trust in the transaction.
3. We can avoid callback hell by attaching callbacks to promise chains in vertical fashion.
Thank you Akshay for this wonderful and knowledgeable video 🙏
A promise is an object that represents an eventual completion of an asynchronous operation. We use it to avoid inversion of control and call back hell. Thank you so much to explain it in a very pleasant way.
The excitement you show to explain us is remarkable! ☺️❤️ Please continue the pace. 😊😁
Awesome Series! I am not a huge fan of watching courses, but I was really blown away.
And I did learn the definition of a promise.
-> A promise is an object which is a representation of eventual completion and rejection of an async operation.
-> We use promises because it prevents us from callback hell and inversion of control. By the introduction of .then() (promising chaining) we have control over our program. Because when we use .then() we attach a callback function to it and don't pass a callback function in it, so we have control of our program/function.
Excellent explanation and tutorial. I'm confident that everyone can comprehend Promise if they pay close attention. An excellent Promise tutorial.
There is absolutely no doubt that you are the best when it comes to the explaining any topic. If someone go through Namaste JS season 1 and 2 then they can crack any tech interview for sure. Thanks a lot for this initiative and making us fall in love with JS.
Only one complaint, the gap in between release of 2 videos is little longer. We all became so eager for your next video but this gap haunts us. If you can do something with it, it will be very good
Thanks again. God bless you with lot of success in your life
Thanks from bottom of the ❤, explaination dil chu liya, keep it up... Eagerly waiting for next episode.
Thank you so much for supporting my channel, Abhishek. This means a lot. ❤️
I love the way you teach, before your promise tutorial i was not able to summarise promise after your tutorial i am not able to forget promise,
now the definition:- Promise are object that represent the eventual completion or failure of asynchronus operation.
First of all, Thank you Akshay for your hard work to explain JS in a easy and understandable way, coming to the HW you gave:
A promise is an Object which represents an eventual completion of an async operation.
The Big advantage is that we can be rescued from the callback hells and also we have the control of the programme. Also promises helps us to resolve the issue of Inversion Control and we can have the programme in a chaining way using the then method.
Promise is an object representing an eventual success or failure of an asynchronous process.
Promise is immutable, it cant be changed hence secure, it resolved callback hell problem,
Thank you for such a deep conceptual knowledge sharing Akshay :)
Hello Akshay bhaiya, I have completed 💯 % of namaste JS session 1, and my confidence level is very high, now I am fall in love ❤ of JavaScript, Eagerly waiting for promise and async awaits.
I am thinking can you start a new series of DSA along with JS so it is very helpful,
as you are teaching any topic in very deep.
Yes, we need DSA series also please.
Same brother
Yes Bro please start DSA session as it's required to crack product based interviews please 🙏🏻
yes plz namste DSA
Yes please
had watched many video on Promises but no one had explained better than you... great video
I love the way you explain the complex stuff so easily and literally enjoy while doing it :)
No one can beat your lecture content , passion of teaching, your energy
Dope content as always 🔥🔥🔥
Thank you very very much for this series. Literally falling in love with JavaScript by getting to know it better.😍
Was waiting for this video for a long time.😭
Please async-await next.🙏
Amazing video ❤ ❤
1. Promise is an object that represents eventual completion of an async operation
2. The promise help us to get the rid of pyramid of doom i.e Callback hell
Promise is an obejct thats represents the eventual completion of an asyn operation. Thanks to you, I learned JS more deeply now that I love Javascript
We need more tutorials from experts like you. How I wish there's some standards for tutorial videos on this platform so people won't waste their time.
Would you care to create a ReactJs series? It excites me to see how you will deep dive into each topic. Please keep it up and don't be conscious with
time. We appreciate your work man!
Assignment:
My understanding: Promise takes output of a function as undefined obj(as a container value)to be assigned actual output values at a later time. This allows for a guaranteed execution
of a callback in an ASYNCHRONOUS OPERATION.
Definition: Promise is an obj representation of an eventual completion or failure of an asynchronous operation:)
1. A promise is an object that represents the eventual completion of an asynchronous operation.
2. Promises helps in handling asynchronous functions, they can be user over callbacks which are not trustworthy due to inversion of control. Promises also helps in making the code more readable and we can use promise chaining instead of getting into callback hell.
Your teaching skills are amazing and your passion for Javascript is contagious! Thank you for the videos :]
Promise is an object representing the eventual completion or failure of an asyncronous function.
As trust is the core of relationships, promises provide trust from an async function to an object.
Promises can only be resolved once and promise objects are immutable.
We could avoid the callback hell(pyramid of the doom) by writing codes in promise.
In callback functions the the functions are passed inside another function, where the complete responsibility of fn depends on the web api(aka inversion of control) or other fn where as in promise the callback functions are attached to the web api.
finally trust is everything.
Great work akshay .
Thanks a lot
Promises are important because they help us avoid the problems we face with callbacks, namely inversion of control and callback hell. Also, promises, once resolved are immutable; thus building up immense trust. Promises are very beautiful.
Hi Akshay,
I think not me, every developer are waiting for your videos so that we get a clear picture of JavaScript.
Thank you so much for your knowledge
Yes,
A promise is an object which represents the eventual completion or failure of an async operation.
this heavy defination now fit in my mind.
video is great, At the end funny touch of cramming "The Promise object represents the eventual completion of an asynchronous operation".
a promise is an object representing the eventual completion or failure of an async task.
Importance of promise:
1. to prevent callback hell
2. prevent inversion of control
3. generate trust
A promise is an object hat represents the eventual completion of an asynchronous operation.
What an explanation.. you are a gem for many learners!!
Promises are the object that show eventually completion or failure of an asynchronous operations. It has two properties ie, promiseState and promiseResult. In another words we have a promise object that will eventually fill and the callback function that were attached to that promise object.
Promise is importantly when we are looking to fetch data from api and then we want to execute few functions based on that value. The best part of promise is we can't mutate the value of promise object.
Promise is an object representing an eventual completion or failure of an asynchronous operation. YEAAHH I learned it
What is Promise?
Promise is an object that represents eventually completion of async() operation.
Importance of Promises:
Trust worthy, Inversion of Control(IOC),Promise chain, States(Pending, Fullfilled, Reject)
Thank you so much brother for an awesome explanation ❤
promise object represents eventual completion of asynchronous operation
Promises help us to solve problem of callback hell and inversion of control
your content is awesome👍👍👍👍👍
What a Great Explaination! hats Off To YOU ❤..
You made my day more meaningful..
Thank you sir😊😊😊
Thanks alot for teaching JavaScript in depth with so much passion. It has really helped alot and very grateful for your videos!
Thank you so much for supporting my channel, Arpit. This means a lot. ❤️
ohhh man i cant believe it i watch the whole 39 minute video without a single pause. Seriously love it
♥️
bro your explanation is the purest form of simplicity
there no boring at all while watching your videos continually and easy to learn thank you
Please be consistent, love your content always.
Your energy is unparalleled. Hands down the best content on youTube. Thanks you for making 'Promises' so much easier and fun!
@akshay saini bhai, one thing that keeps your videos watchable again and again is the little humor that you add.
Thank you so much for what is to me the best explanation for Promises I have ever heard.
Finallyyyyyyyyyyyyyyy..... THE WAIT IS OVERRR... CAN'T ARTICULATE MY EXCITEMENT INTO WORDS... JUST GRATEFUL... THANK YOU SO MUCH AKSHAY SAINI 🙏🙏🙏🤩🤩🤩🔥🔥
Promises are javascript object representing eventual completion or failure of asynchronous operation.
Promises are used to overcome inversion of control and callback hell.
promises are in three states pending ,fulfilled and rejected.
promises are also known as future container for the data.
Thanks brother for this video.....
Thanks a lot.
For the first time I understood Promise in this clear way.
Thank You for such a beautiful explanation and just to mention loved the last 20s of the Video. Thank You
A primise is an object that represents an eventual completion or failure of an asyncronous operation 😎We use them to avoid callback hell, and inversion of control 😎 thank you, guru 🙏🏿
Thank you for sharing such valuable content!
Thank you so much for supporting my channel, Meghana. This means a lot. ❤️
Hi, you are teaching the javascript in amazing way & the concepts are so clear to understand,
Can you please cover the more topics which are asked in js interviews like arrays, spread & rest operator, debouncing, throttling, memoization, prototypes,etc
Assalam O Alaikum,
You are my great and wonderful mentor in teaching JavaScript. You are such an amazing talented person to teach students from your experience. Huge respect and love from Pakistan 🇵🇰
Please consistently upload videos🥹, so that we can able to sync with previous video reference and examples.
Thanks! And please continue this series
Thank you so much for supporting my channel, Ashutosh. This means a lot. ❤️
Best video on promises so far I have seen so many videos.
Thank u brother
Promises is an object that represent eventual completion of async operation
Promises help US resolving issues like call back hell and inversion of control
Thanks for best explanation
A promise is an object that represents the eventual completion of an async operation.
Promise : A promise is an object which represents the eventual completion or failure of an async operation. Advantages : - Prevents inversion of control & build confidence (Though the responsibility to complete/fail a task remain on the piece of code returning promise only). - Ensures the immutability of data. - Ensures that whatever needs to happen on completion of an async task gets only called once (no matter how many times a promise is resolved or rejected).
I appreciate & salute the passion you have for teaching...!! Loved your teaching. Learnt both JS and ReactJS from you.
Thanks.
the end 😆 I will remember the definition for life. Love this video
Thank you Akshay for such a great work..
Thank you so much for supporting my channel, Maruthi. This means a lot. ❤️
Thanks!
Thank you so much for supporting my channel, Anuj. This means a lot. ❤️
@@akshaymarch7 good work bro😊
@@akshaymarch7 Thank you so much bhaiya for teaching us in such a wonderful way. I am also fall in love with JavaScript because of you.
@@akshaymarch7 bhai decorator closure p bna do arrow p pls sab depth me , decorator jo lgta python me, bhai pls es6 major intrvw hisab bna do 30-30 min wle various topics
Mane kafi try kiya par mujhe video trim karne ka koi solution online nahi mila JS se.. Jo mila h usmein ya video blank aati h ya phir trim nahi hoti... Please help me.
Your explanations are just amazing Akshay...Thanks a lot for this kind of explanation.
your explanation was very nice to listen and understand what you are tolding for us
1.Promise is an object which represents eventual complition of an async operation
2.Managing miltiple asyncronous operations and preventing callback hell and unmanageable code
31:10 "we always return a promise from a promise when we are chaining them"
Tried to understand Promises for the last 1.5 years, but patiently waited for this video to understand it one day from Namaste JS and finally this beauty❤.
All I understood:
A promise is an object that represents the eventual completion of an asynchronous operation.❣
Promise states - Pending, Fulfilled, Rejected💕
Use .then() function on a promise object and get the data object once the promise is fulfilled. 💓
Promise Chaining💝
A promise is an Object , and that object represents the eventual Completion or Failure of an Asynchonous Operation. Thats It , Thank You Akshay Bhaiya
The Best explanation that I have ever heard..Thanks for the nice and valuable info..keep it up brother
FIIIIINAAAAAAALLLLLLLLLY!
I wait so long for you sharing your thought about this topic! LOVE FROM ARGENTINA!
You have taught me so many things brother thank you so much :)
Thank you so much for supporting my channel, Sailesh. This means a lot. ❤️
Superb explanation. Thank u so much Akshay sir for these videos.
Love you explanation, you made understanding promise really easy. Thanks, really Good job 👌
1 - Promesa es un objeto que representa la eventual complecion o falla en una operacion asincrona.
2 - Porque evita bugs, errores, dublicaciones y otras complicaciones al depender de una lista de callbacks de las cuales podemos no tener control, ademas produce el efecto de callback Hell, que hace que el codigo sea complejo de leer y mantener, ya que crece horizontalmente.
Promises helps us to keep control of our code with us, instead of passing control to another function.
Promises ensures that our function is executed only once.
Promise object is immutable, so we don't need to worry about it's immutability.
It helps prevent callback hell, through promise chaining.
It only has 3 states only: "Pending", "Fulfilled", "Rejected".
Promise is an object which represnts eventual completion or failure of an async operation.
Thank you Akshay!
Promise is an object which represents eventual completion or failure of asynchronous operation.
And Thank You 😊😊
At 16:57, we can print the promise object using console.table() to see the state (pending) and result [at the time of logging]. Since expanding a object will always show the current value rather than at the time of printing. By using "console.table", it prints the values at the logging time and provide an option to view the current value beneath it.
helpful tip
38:44 that promise definition matra is heard even in my sleep now😅. Superb edit.
The Myth, The Legened, The Miraculous: Akshay Saini!
Promise is an object that represent the eventual completion of an asynchronous operations. :) You are awesome bro.
The way you are explaining a topic is very good really I love it ☺️