Creating a blockchain with Javascript (Blockchain, part 1)

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Күн бұрын

Learn how to write your own Blockchain with JavaScript. In this video I'll show you what is behind a blockchain by using simple code. It's not a complete implementation, but enough to understand how blockchains work and how they guarantee that blocks can never be changed.
After creating our blockchain we'll try and tamper with it. This will demonstrate a blockchains ability to detect fraud.
Next video (implementing proof-of-work):
• Implementing Proof-of-...
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Пікірлер: 1 000

@tauwheed3055 6 жыл бұрын

I do not understand anything about coding, but the way this mysterious gentleman stated everything, I was completely hooked up seconds by seconds till the end. I guess some peoples do have some extraordinary quality of teaching. Thanks Savjee

@ViralVeediuh 5 жыл бұрын

Tauw heed it’s that you actually care about learning about blockchain. Trying watching a video on programming a microwave keypad. Much less interesting lol

@BigDaddyDax 3 жыл бұрын

Agreed!!

@BigDaddyDax 3 жыл бұрын

@@ViralVeediuh true

@aayushpratapsingh5860 2 жыл бұрын

Same here

@pajamasoverpeople4412 2 жыл бұрын

SAME.

@vegn_brit5176 3 жыл бұрын

Great video. I'm a programmer so this made a lot more sense to me than watching someone try to describe how the blockchain works in a spoken presentation!

@FacundoTroitero 2 жыл бұрын

After +1 year of courses, projects documentation and tutorials I could finally understand how Javascript classes work thanks to this video. Thanks!

@owenparker6651 6 жыл бұрын

Savjee, I have finally been compelled to subscribe to a youtube channel. As an 'old dog' programmer, you have got me moving on blockchains more than the dozens and dozens and dozens of articles I have read. For a 'show me' programmer, this is just what the doctor ordered and I thank you for taking to the time to share your knowledge and for doing such an easily understood walk-through. Well done young man...

@simplyexplained 6 жыл бұрын

Thanks a lot! Reading your comments made my day!

@prabhusingh7481 6 жыл бұрын

Demystified this for me, finally! Thank you so much for making these concepts so tangible.

@lucysluckyday 4 жыл бұрын

My gosh, in terms of covering the basic fundamentals this is an amazing intro!

@blackswan7568 Жыл бұрын

For my internship, I was recently requested to do a simple web3-based project. This is what I've decided to use. Thanks for this project and for being a great teacher😁

@Procyon58 6 жыл бұрын

So much information fit in this 15 minutes and this finally made blockchain click in my head. Thank you for this!

@niklavr 6 жыл бұрын

Yes! Really helpful video! Thanks!

@luckyadeloye3452 6 жыл бұрын

Especially the explanation of difficulty and nonce.

@seanrosen9855 6 жыл бұрын

Exactly! Over all those explanations online which doesn't provide any example, I can finally understand the base concept of a blackchain after watching this video, thank you soooo much. Autosubs

@nitinchaudhary7686 6 жыл бұрын

How can i make zsh in terminal

@stanicng 6 жыл бұрын

Same here. I think we belong to developer world. Simple words can't make us understand until read the programing logic. Hehe.

@jessss7792 6 жыл бұрын

Very well done video. Steady pace, clear code, and an engaging voice. The blockchain just became a whole lot less intimidating and mysterious, so thank you.

@saxenaabhi 6 жыл бұрын

Oh man, after watching heaps of videos on bitcoin, etherium and block chain. This is the first time I really got my head around only because we think in terms of code. Love you for that.

@joeysipos 3 жыл бұрын

yeah, seriously. All these explanation videos make no sense. But looking at how the code actually works make perfect sense haha.

@astrarai-thesobercoder 2 жыл бұрын

Same here 👨🏽‍💻

@jasonpatel6562 Жыл бұрын

@@joeysipos if(currentBlock.hash !== currentBlock.calculateHash()){} TypeError: currentBlock.calculateHash is not a function : thats the error I got, not sure why it is function

@TheStoriesProductions 3 жыл бұрын

"Simply Explained" indeed ! Amazing, cleared a lot of concepts.

@clementbourcart785 3 жыл бұрын

Love this! Thanks so much for making this tutorial, really helps a non-techie like me get under the hood of blockchain!

@Ricardoromero4444 3 жыл бұрын

Damn bro, that light theme doesn't hurt your eyes?

@snikkerrr286 3 жыл бұрын

😂😂😂😂

@hansphung 3 жыл бұрын

and the bracket on the same line with the parentheses and no space, ew

@slavento 3 жыл бұрын

Try working in very light room...it's common to work with light theme in that case, and with dark theme in darker rooms...

@rangarajann1781 2 жыл бұрын

@@slavento yeah using dark theme in bright light environment is not good. Dark theme is perfect for only dark environments. And light theme is good for brighter environments

@jorgepvenegas 2 жыл бұрын

Does anybody know which theme is he using?

@sicko_drops 6 жыл бұрын

great video. subscribed!

@AkhilPrabhakaran 6 жыл бұрын

Wonder I didn't come across your page months ago. Not just for this particular video but the quality and the clarity in all your videos are amazing. Huge fan!!

@dukewellington5222 3 жыл бұрын

Explaining it in code makes blockchain technology so much easier to understand. Thank you for this! Great job!

@vasanthkumar2190 4 жыл бұрын

This looks similar to linked lists in Data Structure with added security!

@cazino4 3 жыл бұрын

Great observation!! It is similar to a Singular Linked List data structure With one massively important improvement namely: O(1) (i.e constant time access) to all blocks in the chain, via the top-level array.

@Mailmartinviljoen 3 жыл бұрын

May i nitpick? The focus is on integrity which make it inherintly secure 😁

@frumpledpigskin 3 жыл бұрын

i was thinking the same thing

@SatyamGupta-gc9sq 2 жыл бұрын

@@cazino4 yup it's linked list but not singly linked list, it's doubly linked list as it stores the adress of the previous block too.

@cazino4 2 жыл бұрын

@@SatyamGupta-gc9sq Nope, you're INCORRECT!! Please revisit the source code - it is quite clear. The presented Block Chain data structure has more commonalities with a SINGULARLY Linked List, NOT a doubly linked list as you have attempted to suggest. Whilst I agree that the structure does indeed store reference to the previous node (i.e its parent) it DOES NOT *DIRECTLY* store reference to the NEXT node. Thus it's essentially a singularly linked list in reverse.... But STILL a singularly linked list nonetheless. Source: myself lol. I've actually built these types of core data structures (i.e Singularly/Doubly linked lists, Binary Search Trees, Balanced Binary Search Trees,Tries,etc) from scratch in numerous languages and have a deep understanding of matters pertaining to their. respective implementations,trade-offs, time-space complexity,etc

@slapassdevil 7 жыл бұрын

First! Also great videos man, thank you so much!

@simplyexplained 7 жыл бұрын

+Anthony Dutra Glad you like them! (And wow that was fast!)

@nestoreduardoirahetamazari9409 Жыл бұрын

Great! I was learning blockchain but with a traditional school teaching for weeks and I didn’t understand nothing but with your videos I completely hooked up great and very simple way to learn thanks and appreciate to share your knowledge ❤

@luizdrumonddeandrade7065 5 жыл бұрын

Just amazing how you have explained this topic in a really easy way. Congratulations!!!

@classborn 4 жыл бұрын

Subbed , you brought tears to my eyes.

@kukuster 3 жыл бұрын

exactly. That's why dark theme *is better*

@hashmoody 5 жыл бұрын

Really great, that sparked a great idea in my mind! :) (y)

@FreedomForKashmir 2 жыл бұрын

I swear, this is the video finally where I really understood the concept of Blockchain. I have watched many videos but was getting just repetitive things time and time again. Thank You very much. I have like and subscribed to you channel.

@fernandofradegrada 2 жыл бұрын

Very clean explanation, and also very clean english for those who doesn't speak english natively. Thanks!

@simplyexplained 2 жыл бұрын

I'm not a native speaker myself, so I have to keep things simple ;)

@AmitYadav786 6 жыл бұрын

Awesome intro, I think you should make this a series so that people can make their own full blockchain using your details. When is the next video coming??

@simplyexplained 6 жыл бұрын

+Amit Yadav Great idea! Next stop would be to discover smart contracts. Definitely will work on that in the future. But first I need to finish another course ;)

@simplyexplained 6 жыл бұрын

+Amit Yadav Great idea! Next stop would be to discover smart contracts. Definitely will work on that in the future. But first I need to finish another course ;)

@nitinchaudhary7686 6 жыл бұрын

Amit Yadav how can i make zsh in terminal?

@stanfordnwosu424 6 жыл бұрын

Simply Explained - Savjee Heyy any luck with making those blockchain courses

@JavaScriptRoom 5 жыл бұрын

Hey! Thanks for the great content! One question: why didn't you generate block's index and timestamp on a fly in the constructor? Is there any reason for passing them on instance initiation?

@oderingpush8054 2 жыл бұрын

hello, has this improved your knowledge of java and blockchain? have you made any progress on creating a blockchain? i would like to talk with somebody who might be able to help me script a source of a new blockchain

@ulfkarlsson272 6 жыл бұрын

Thanks, I had the theoretical understanding of what a blockchain was before, but seeing it explained this way makes everything much clearer.

@joyhearrington8503 Жыл бұрын

You are a great teacher, Mr. X! Thankfully, I do not have to write this code but I needed to understand blockchain for my graduate class. This video finally made it all click! (I watched your other one before this too and that was helpful as well.) Keep up the great work and thank you for sharing it for free!

@mi13estrellas 6 жыл бұрын

would implementing some of those other features such as "proof of work/ stake", check of funds, ability to prevent tampering of data / rollback function be possible to demonstrate in another video? It would be greatly appreciated.

@daezohn8662 6 жыл бұрын

Not to mention P2P network consensus and transaction broadcasting. I sometimes think writing your own blockchain is just as ambitions as writing your own OS. Maybe it is just easier to take to bitcoin code and adapt it to your needs.

@utopialabsvideos9408 6 жыл бұрын

@Sophie, do you want a complete implementation? Just read the source code for Bitcoin or Ethereum...

@lucysluckyday 4 жыл бұрын

Yeah the actual source code is the best option when you want to understand the more complicated aspects of merkle trees, nonces, unconfirmed transactions, and memory pools. But this is an extremely good generic intro on the fundamentals !!!

@SwadeshiBakchod 5 жыл бұрын

13:02 Blockchain is like "Mr.Stark...I dont feel so good..."

@SubhrajitSadhukhan 3 жыл бұрын

Thanks man. This really helps understand the concept without going into too much or too little details. Exactly what I was looking for.

@CourtneyZinckgraf 5 жыл бұрын

I know nothing about coding, but this example really made me understand what's happening with blockchains - thank you!

@jekabolt 7 жыл бұрын

it's will be great if you create a. video about smart contracts

@simplyexplained 6 жыл бұрын

That's a nice idea! I'll definitely consider that!

@python_tutorials6519 6 жыл бұрын

yeah pls do that and can u include dates in smart contracts for tokens to be distributed only during that time?

@simplyexplained 6 жыл бұрын

+Python_Tutorials Great idea! I'll think about how to implement that :)

@python_tutorials6519 6 жыл бұрын

great,thanks a lot and we would love to wait for that video

@arhabersham 6 жыл бұрын

WORD!

@albertkeller3773 6 жыл бұрын

How can I download the library on Windows? Because on windows the terminal is working with powershell

@AbdulAhad-ni4hq 5 жыл бұрын

same problem here did u solved ?

@safaelboukhari5431 5 жыл бұрын

@@AbdulAhad-ni4hq same probleme :(

@alvarovalenzuela7389 5 жыл бұрын

use bash instead :)

@eoussama 5 жыл бұрын

You need npm installed.

@robincard1548 5 жыл бұрын

If you're really serious, I would switch your desktop from Windows to Ubuntu Desktop (free) or run Ubuntu in VirtualBox (free). Windows and Node/Javascript don't play well yet, there are still lots of problems with file names and stuff. The windows guys I work with are always having problems, the people on the *Nix/Mac system dont have these problems ever. I'm not saying Linux/Mac is better than Windows, just saying that for now JavaScript is better on Linux/Mac. They my fix it soon.

@mauriziomaisto2874 6 жыл бұрын

Great tutorial, thank you. I was "playing" with your code and i've just discovered that changing the "Genesis block" (block 0) attributes is possible (the chain stays valid). This is due to the "isChainValid()" method; as you can see, the method has a "for(var i = 1; i < this.chain.length; i++){ [...]" which starts from "i = 1". This means that no controls are applied to the first block (data can be changed without any problem). A simple work-around is to change the "for([..])" loop (make it starts from "i=0" and check the previous block only "if(i>0)"). Thanks for your time and knowledge

@itshiraljain 2 жыл бұрын

You simply explained and I simply subscribed. This is what I was searching for as I don't knew any implementation of blockchain. thankyou

@mattyzacharia 6 жыл бұрын

Great video. Congratulations. I have a question though, in the example, I tried to tamper data and did recalculation of current hash and assigned to existing hash. I got output as true. We are not tampering anything with previous block hash. Basically I have not understand the check on current block hash with the previous block hash as for me it always return true. Also if I carefully watch video , when you do a tampering and set current hash. It gives output as false. However if I examine your console which is on this video, both previous hash and current hash seems to be identical. Then how does it return false? Thanks Matty

@dukewellington5222 3 жыл бұрын

Did you put the return true statement in the body of the for loop?

@mzaki8503 3 жыл бұрын

I am having the same exact problem now. Did you manage to solve it?

@Chris-oe4pj 3 ай бұрын

when isChainValid loops and checks the block that is right after the one you changed, its previous hash will not match that preceding block's new hash that you had calculated

@calvinlin6670 6 жыл бұрын

It's a great explanation video of Blockchain. Can you tell what IDE you are using 0.0 Cuz i really like the UI , thanks

@RoadToFuture007 6 жыл бұрын

Hafrn The Grey white edition ;)

@MistaT44 5 жыл бұрын

Press ctrl k + ctrl t, and select the quiet light theme :)

@ib6435 3 жыл бұрын

Watching this in 2020 and its broadens my programming knowledge. Thanks!

@lovebajpai5288 6 жыл бұрын

Fantastic!!! What an explanation! it just makes you understand the whole thing in one video!

@laude94wuo 5 жыл бұрын

Clear coding style makes a complex concept to be so easy that everyone can understand! Amazing...!

@joshuacoll.6100 5 жыл бұрын

BRUH thank you so much!! I needed a simple implementable example with the core concepts intact!! Thanks again dude you are the best!! :D

@mstafadev6729 2 жыл бұрын

I've watched too many videos to understand what a blockchain is and none of them seemed to help, but this video clears things up in my head about blockchain, Thanks

@adriancelis9691 4 жыл бұрын

This is amazing. I dont even do Javascript (just php) and i understand what you're saying. Great vid.

@breal1460 3 жыл бұрын

Thank you for sharing this. Today I decided to learn about blockchain. I hope I can learn enough to produce something to help make our world a better place.

@rkj541 4 жыл бұрын

Greatly explained the concept in a short video, great job!!

@jagodiving 2 жыл бұрын

there were a few genious on algorithm n coding, but i think you one the best amid them....simple n clear

@tharhtoo2149 2 жыл бұрын

Thank you so much, Sir. You just make the whole concept of blockchain sys clear for me in just under 15 mins.

@gazisalahuddin8907 2 жыл бұрын

Great, you understand concepts through building them. Thanks, man.

@MadhavanR 3 жыл бұрын

Noticed this video on my recommendation and in 15mins understood the basics of blockchain… most importantly the simple and powerful sample you showed👍🏻👍🏻👍🏻

@shivaskanthan6144 6 жыл бұрын

Excellent 11/10. Detailed, concise and easy to understand.

@bhag1 6 жыл бұрын

This is great. Simple and crisp. Thanks!

@AhmadNasikun 6 жыл бұрын

Thanks for the great tutorial. There are lots of videos describing how blockchain works, but only a few that give some technical example(s). Among those few, this video stands out really well. For those who are new to blockchain (e.g. me), this video is really enlightening.

@leezhenjian7451 Ай бұрын

Very intuitive way to explain about blockchain. Thumbs up!

@mubafaw Жыл бұрын

Wow! This explanation demystified the whole concept of blockchain . Thanks 😊👍

@fastindemand6074 6 жыл бұрын

This video was simple and informative. thank you.

@ipungdevacademy 4 жыл бұрын

Wow very simple explained ! thanks sir you are save my life!

@germandiagogomez 6 жыл бұрын

Very nice introduction. Perfectly explained concepts in a compressed timespan.

@sreelalts1892 4 жыл бұрын

Amazingly explained! I really didn't know anything about Blockchain. After watching this video, I was like "wow, this guy is amazing!". You did it so nice Savjee! Thanks a lot!

@amnest1ac 5 жыл бұрын

This is so easy. For all the noise this "technology" has made. I am impressed how fundamentally basic is the idea itself.

@mehdivand2977 3 жыл бұрын

he explained in a simple matter , thank you

@lakshmiprabha8271 2 жыл бұрын

simply explained a complex code. Love this video

@Bagga4u 3 жыл бұрын

Thank you for clearly and efficiently explaining the concept of block chain. Now it makes sense :)

@NightShadow69420 3 жыл бұрын

Finally understood how magic internet money works. Awesome video!

@md.jayeenbinalam.6194 2 жыл бұрын

The best beginner level blockchain tutorial.

@VincentNoben 6 жыл бұрын

This explanation is so solid! Like others said in the comments, this is what made me get it. I sortoff knew but this made the click and will make it much easier for me to explain it myself in the future. Thanks!

@marcelosabadini 6 жыл бұрын

Best 14 min of the year!! tks a lot!

@funmeister 5 жыл бұрын

Absolutely love this video. Only regret is why I just found you now. Subscribed!

@thejmcexperience8755 6 жыл бұрын

Thanks for the series. This has helped me understand blockchain.

@mauriciogambini 4 жыл бұрын

simple, objective and complete ! Thanks :)

@zhangbruce4815 6 жыл бұрын

Best block chain explanation video so far I've seen

@Superb_virg 5 жыл бұрын

Extremely simple and well explained amazing.

@stevenzhang8620 6 жыл бұрын

Very well explained blockchain in simple javascript code! Thanks a loooot!

@Mailmartinviljoen 3 жыл бұрын

Clarity by far the best tutorial i have ever seen

@WhatIsThisAllAbout 6 жыл бұрын

thanks man...I was wondering how this works in code & thats what you explained so clearly.

@chunkin9799 3 жыл бұрын

Clutch video. Excellent explanation of block chain. So much simpler of a concept than when you just hear it explained.

@KusaasiraNoah7421 5 жыл бұрын

So much info in just under 15minutes. Thanks

@dj_averion Жыл бұрын

Easy explained and good to follow. Thanks!

@josephcobbinah5412 3 жыл бұрын

The first video about Blockchain that I actually understood

@Frank2tek 6 жыл бұрын

Best and simple way to understand the core concept of blockchain . Nice job ...

@torbilan6292 6 жыл бұрын

Thanks , such a clean code and clear speech. Benefited a lot !

@tcjusttc5418 6 жыл бұрын

This is a great video. Concise and easy to understand.

@jacob_dmn 2 жыл бұрын

so so helpful, I can't believe all that happened in 15min. Love it. Please keep it up

@OJB42 2 жыл бұрын

Very easy to follow and succinct. Well done!

@Shortly8908 6 жыл бұрын

Thanks bro. I imagine blockchain works like magic until i watched your video.

@MnappsNET 3 жыл бұрын

This videos is just awesome, everything makes sense now, thank you!

@gogoikabir 4 жыл бұрын

amazing, now I understand something about blockChain

@prithvidheer6893 4 жыл бұрын

Loved the explanation. You got a nice way of teaching.......Thanks :)

@mizlagunesvary5077 3 жыл бұрын

Wow.. Thanks, Sanjeev for this video. I`ve been searching for something to enlighten my brain with what`s actually Blockchain is. Finally, you did it... Thanks man

@PlatinumBuckGorilla 3 жыл бұрын

This is a top notch video mate. Tomorrow I’ll get started.

@Memories_1984 6 жыл бұрын

clean example, clean explanation. hearty thanks enclosed in my subscription

@claudiograsso 5 жыл бұрын

Excellent!!!! Thanks a lot for such a clear explanation.

@gurzimm3213 3 жыл бұрын

I don't even know how to code but this video made so much sense, great job!

@sanatanmeaning 4 жыл бұрын

Thank you Savjee for free and *high quality* knowledge

@pawelkozlowski6411 3 жыл бұрын

i watched the whole thing ,didnt understand anything but it was fascinating ure a genius

@richaagrawal4416 5 жыл бұрын

for the first time in life i have watched the whole info stuffed youtube video in one go. keep it up man!!

@broonzy2006 6 жыл бұрын

wow! great video... I'm a low level dev and by watching the last 2 videos, really got the concept and quick application. Cool!

@lindadehaan 5 жыл бұрын

I liked this very much! Thanks for the demo.

@braianoso4138 2 жыл бұрын

Love the way you explain things for a noob like me

@Goldy8686 5 жыл бұрын

Thank you so much for giving detail information that is germane to the subject at hand. I’ve watched tons of video on this topic and walked away clueless