Mining rewards & transactions - Blockchain in Javascript (part 3)

[@stevenrossi293]

Can you do the next video on how to make a peer to peer network!

[@GeeksOasis_]

yeaaa please

[@vlad981]

Amazing! Please, keep up making this series!

[@digitalart321]

Excellent! You made Blockchain comprehensible for children

[@javierpernasalvarez2997]

I would say one of the best points of the tutorial are your comments on how things world in real life (Bitcoin) and the relationship with what you examplify here. Nice job!

[@leonhardeuler9839]

I followed the series until this video, now my mind is actually blown up.

[@HomesteadAce]

Awesome series! Just a note, in your minePendingTransaction method you forgot to set the previousHash of the block as you did in the addBlock()

[@curious_one1156]

Yeah. Exactly, why did the function still work ?

[@dotkoon]

​@@curious_one1156 In this video he didn't validate the blocks. But in the next video, the code has been fixed.

[@nathanstroud4879]

@@dotkoon Defiantly weird, I am getting an "invalid array length" error, so this is because of the isChainValid() or mineBlock() function?

[@olegwarkentin2993]

is this series go on? like "how to create a wallet" or synch with clients? :)

[@OmarJIBAR]

Amazing series 👍My area of interest has nothing to do with blockchains but your series captivated me. Thanks a lot.

[@PeterBatah]

Thank you for sharing your time and expertise with us. I will definitely be going to bed a little bit smarter tonight. Have a safe and wonderful day!

[@desireco]

Thank you, this series have been awesome. I am familiar with bitcoin but didn't expect you will be able to cover so much in such short time.

[@ollimac73]

amazing, please continue with these great video tutorials. Thanks for the ones you have done so far.

[@Loschcode]

Absolutely great and simple explanation to how blockchain actually works. Keep the good work !

[@Angelosanto]

These videos are perfect, it would be awesome if you continued the series.

[@itcrespo]

thanks for these videos, the simplest training for blockchain I've found

[@mattha3787]

Please do more, love it.

[@malowwang6211]

Thank you for sharing, savjee! Great videos! Expect much more videos from you

[@AbrarAhmed5]

These videos are amazing! Please keep them coming.

[@frediopratamad2349]

Thank you savejee, your explanation was given from heaven :D Amazing

[@wildtigers1210]

I think `getBalanceOfAddress()` should also check the balance of `fromAddress` ? before deducting coin from it ?

[@thejoker585]

Mining reward should be added to the current block being mined. It is logical to think that a miner would like to get paid the second she verified the block and not wait for the next block, otherwise theoretically she will have to pay a fee (in BTC network that is both expensive and time consuming).

[@thejoker585]

But otherwise a great tutorial!

[@frknbasaran]

Thanks for this great series. I just joined your channel but you definitely deserve more.

[@Chino747747]

great vid and tutorial, please keep on adding to these. I'm sure they'll be very popular

[@dec41rus]

Savjee, your explanation is great. Thank you very much

[@yuichibencoolenhrs5527]

Thank you for this video. Please continue this series and I look forward to (Part4) (Part5) and so on.

[@AkhileshJain0605]

Great work Savjee. Would really love it if you explained the ethereum blockchain in your videos!

[@rleevzlno]

Yeiiii I was waiting for this! Thanks for keep uploading :)

[@ongxa888]

Thank you very much ! Your explaination is simply and easy to understand !

[@wrekktime]

you left "this.index" in calculate hash :)

[@simplyexplained]

Yep! I fixed it on GitHub together with some other issue's... Sorry about that!

[@sauro28]

where can i find it?

[@MenOfPurposeHQ]

Please add more to this series!

[@Jonathan-br8dn]

Hi, fantastic series, I am eager to see new videos. regards!

[@mahdipakravan676]

This is Fucking Best Quality OF Learning Blockchain !

[@josephnyc]

I wish everyone in life was explained in OOP, damn fun to watch. Keep it coming, create a Wallet class Savjee! I’m curious, did you make all properties and methods public just for the tutorial? The Chain and Block classes are so exposed it would be very simple to alter, no? IMHO the properties should be private at the least.

[@simplyexplained]

Yes everything is public. Javascript doesn't have 'private' properties.

[@josephnyc]

Savjee I’m aware, didn’t literally mean public/private, I meant public as in own property, and thought there were ways of achieving private properties with symbols, closures, weakmaps, etc., was just curious to your thoughts on this. I dunno. Love the tutorials!

[@rorythewriter]

@@simplyexplained How do you make properties that can't be changed in Javascript then? Sorry, I'm not used to js, so not having private seems counterintuitive

[@simplyexplained]

There isn't a good way to do that in Javascript. Most people prefix private variables with an underscore to show that they shouldn't be directly accessed.

[@daniellaerachannel]

Excellent man! great tutorial

[@ryankdavidson]

Great video series, short and sweet

[@ThomasOrlita]

Nice video! I don't need to create a blockchain in javascript, it's just interesting to watch it... Subscribed to catch new videos! :) Btw you forgot to update this.index and this.data on line 21. (ok I see that it's fixed on github)

[@sikwee]

Can you do a video on how to implement proof of stake in a javascript blockchain?

[@owaisali124]

so basically when a reward is given to a miner, it is added in pending transactions, but on second iteration it again adds reward for the miner and this will not end, the whole chain will look like reward of the miner of mining his own reward

[@darrenlefcoe]

works, well done. good education... look forward to next video.

[@swapnilgt]

Nice demonstration. Thank you!

[@curious_one1156]

The previousHash is not included in this code. He removed the addBlock method with the minePendingTransactions, but did not assign previousHash before mining the block. Besides, he did not remove the index from the hash calculation. He is surely running git code, not this one shown. This would generate an error in the hash function.

[@yourlifeonpower]

Bro! Please develop this tutorial into a course package! I will be very happy to pay for your course and learn from you!

[@yourspanishstories]

Thanks, now I'll go make my own crypto currency.

[@simplyexplained]

Please don't...

[@disnelson308]

I love your tutorial. It is simply t]one of the best here. Please can you build a UI to interact with the application. And consider adding a P2P network too. Thanks

[@adlvlaw]

Very clear, top quality videos!

[@Glosoliful]

Loving video! You really know something only if you can explain it to your old mother or you can code it!

[@rd9055]

Great video! Please make a video on Tor in simply explained series

[@ceorecdeclec9774]

Will you add private/public keys and how can you implement the peer to peer network

[@Metachief_X]

Hey Savjee. Can you make a more detailed video in depth about how to actually do peer-to-peer trading?

[@5906646]

Fabulous! Great Work! Tahnk you

[@joeysipos]

So a bitcoin block is basically a big block of transactions... ah ok, makes sense. Didn't know that before.

[@dawnthomas1723]

The getBalanceOfAddress returns 0 for every transaction. I have checked the code against the code in the video and it does not return the balance as your sample code. Are you running the sample code from the video, or are you running the code from git?

[@curious_one1156]

See, the previousHash is not included in this code. He removed the addBlock method with the minePendingTransactions, but did not assign previousHash before mining the block. Besides, he did not remove the index from the hash calculation. He is surely running git code, not this one.

[@as269]

the same issue i face did you resolve it?

[@PendemiGod]

Great work thanks so much!

[@priteshvaviya6076]

Hey why haven't we changed the calculateHash function??

[@IbanVan]

Exellent, one question, How i can save the blockchain (transactions) filesystem or DB ?

[@AhmedAdel-ql5dt]

I followed your steps and I am facing the problem , I can't reward the miner and after mining the second block it gives me your balance is 0

[@sunjiangkang5353]

Thanks for your explaination

[@marcellorinaldomartina5593]

Have you forgot to update block.previousHash in minePendingTransactions?

[@Leoninmiami]

yes, he did. I created a "printBlocks method in the blockChain class that prints all the blocks to the console. The blocks are missing the previous hash. printBlocks() { for(const block of this.chain) { console.log('====================== ', JSON.stringify(block, null, 4 )); } } I fixed it as a param when creating the block in the minePendingTransactions method ... minePendingTrasactions(miningRewardAddress) { let block = new Block(Date.now(), this.pendingTransactions, this.getLatestBlock().hash); .... I'll probably need to change it in the next video ... but I'm happy with my solution, for now.

[@BulentSvr]

Dear Savjee, Can you do a Simply Explained Video about "EOS"

[@agr__7]

amazing man, amazing! Good job!

[@18Maxic]

Excellent man , thanks you

[@blackmennewstyle]

Once you started mining crypto-currencies, there is no going back unless your electricity bills become way too salty...

[@Deetoya]

This really Helped.... LOved iT...

[@asolomon15]

This was an awesome tutorial

[@myhandle364]

Wow, this is what I'm looking for on youtube. I'm still curious on (6.38) how p2p network a fool proof?

[@marcwyss8100]

Noob question: Line 52 when you create a new Block: are we not missing the parameter for previousHash? Because when I „console.log“ the blocks, my previous hashes are all at the default ‚0‘.

[@marcwyss8100]

Default value being ‘ ‘ and not 0.

[@rijumukherjee5280]

Hey Savjee I dont understand the concept how miners get out of the loop,Say 'A' transferred X coins to 'B' and now say 'C' mined for this transaction and now again another transaction i.e. reward transaction is obtained and so this will again be mined by 'C' so again it will create a new transaction.....This will continue...So how to break this loop....

[@desireco]

There is one more thing. address1 doesn't have anything to it, so I added a transaction to genesis block which resolved the issue.

[@ShogunWarrior36]

I really enjoyed this 3 part tutorial. Nice work! Xavier, do you happen to be Flemish by any chance?

[@simplyexplained]

Yes I am ;)

[@dipanwitachanda444]

Waiting for your next video

[@scarlettcrofts3168]

How do I solve the TypeError: block.transactions is not iterable ??

[@frankr.3413]

Great! I wish I could coding like you.

[@aigerimiskakova963]

Good Explanation!

[@beunmin6]

Awesome! now i can make an ICO

[@caochihai]

Thanks for your video, it was really helpful for me. Can you explain why we don't have a balance in reality? Why do we have to calculate it by going through all transactions? Thank you so much

[@simplyexplained]

Keeping track of balances would waste storage space without any benefits. Remember: blockchains are immutable. You can't change something that's already inside. If you want to keep track of balances, you would have to do that in every block.

[@jamiegabbay7232]

Apologies, but why is that two transactions are set initially (the add1 to add2 of 100, and the add2 to add1 of 50) yet the 2nd transaction seems to be skipped over? Shouldn't both transactions be completed before xavier recieves his reward?

[@liatris69]

This is gold!

[@rosseaux]

Can you also make a tutorial with a proof-of-stake variant?

[@chrisreilly85]

Can you explain how luck factors into this for a miner? If I understand correctly, the miner is simply changing the nonce until the block difficulty is met (please confirm if I'm incorrect here). If so, wouldn't every miner start at nonce 0 and work up by 1 sequentially, therefore whoever has the most computing power would solve every block? Or, is it more efficient to randomize the nonce? Thanks for a great video series.

[@javajava7475]

Please make a series on making a wallet for our cryptocurrency

[@DeepakSharma5]

Great videos! Helped me a lot in understanding block chain. Correct me if I am wrong but I think this new block chain will not be valid because you are not setting previousHash while creating new block in your minePendingTransaction function.

[@niter43]

He forgot to pass it to constructor, yes.

[@brianjianzhao3238]

Hey Savjee, why we still need to have prevHash as a property for each block and as part of the input for the current hash calculation? It seems to me it never gets used in this video's implementation.

[@stormhess8622]

Thank you for taking the time to make this video...how would I implement an html frontend interface for it? Since it is to be highly secure, is there any specific calling conventions from html to the script or is as simple as an onClick() event to trigger the transaction? Cheers.

[@jackjangdude]

He deletes the addblock method that assigns the previousHash argument to the previous hash, but when he replaces it with the minePendingTransaction the block that gets pushed never includes the previous hash. Maybe I missed something...

[@nileenaj3964]

In the description box, he has mentioned that he made a mistake and forgot to add the previous hash value.

[@gaborzsoter]

Hey, if you continue to run mineTransactions() again and again you actually mining your reward and get rewarded which you can mine and get rewarded infinitely? What am I missing?

[@jayantkhandelwal7326]

Hi, I have a doubt, as we have removed the reference to previous hash when we removed addblock method, then how are we implementing a blockchain without having previous hash value? Please help me in clarifying my doubt!

[@curious_one1156]

IDK myself. Maybe he ran the code from git, and not this one.

[@adhoom]

I don't know whether this changes in the upcoming videos or not. But, something that is really bothering me is that the user specifies the index for his block. Why is it not controlled by like a static field that keeps incrementing when a block is added ?

[@simplyexplained]

Good point. In fact, that index isn't needed at all. It was deleted from the GitHub repository but unfortunately I cannot update videos. github.com/Savjee/SavjeeCoin/blob/master/src/blockchain.js

[@chregig7967]

Wow, thank you so much, I've been struggling with understanding how bitcoin, mining and the blockchain as a whole worked for a couple of years now and your videos finally cleared up so many questions! Now, if someone reads this, I have a question about one aspect that I am not too sure I understood correctly. You said the mined amount will get added with the next mined block, but in reality that would be very counter productive, would it not? Otherwise, nobody could actually make any transactions, because all of the blocks are used up to pay the rewards...? Or am I missing something?

[@simplyexplained]

Ah, well there is only 1 miner that can mine a block. So each block creates just 1 'reward' transaction in the next.

[@masoudkhoda9161]

Nice job. only one question. In your codes, as I checked, you set previous Hash by creating a block. Suppose that, "L" is the current last block in a chain. Block "A" and "B" are created at the same time. So they set their previous hash with the same hash e.g. Hash of "L". What happens by mining when both of them are mined successfully, but B was mined faster. Therefore normally the previous hash of "B" is correct, but the previous hash of "A" should be changed to the hash of "B". What I want to reach, I think assigning previous hash by creating a block is not necessary, but by mining. Am I right?

[@denislupookov7895]

OMG! It is something amazing!

[@ru42112]

Have you done a video explaining the difference between pow (bitcoin) and pos?

[@simplyexplained]

Yes I have... It's going live later today 😂🤐

[@ru42112]

Simply Explained - Savjee that was quick I'll be looking for it thanks. I also don't understand why all crypto projects have to have a coin or token involved in it.

[@der-lotse]

So pending transctions aren't secured by the blockchain before mining. They are "just there" in the system right? They will get commited by a miner when his mining is succesful. Did I understand it correctly? Why could a miner not change the transaction before the mining is complete and therefore no hashing for the particular transactions is established at this point?

[@simplyexplained]

Yes you understood correctly. However each transaction is digitally signed with the private key of the sender. When a Miner changes the transaction, the signature becomes invalid and the Miner can't re-sign it because he doesn't have the correct private key to do so.

[@g_pazzini]

I have a question. Ideally, does a block contain multiple transactions or only one? if it's multiple, are the transaction grouped by certain parameter (e.g. contains transactions with the same fromAddress), or just random?

[@VoTinhThuong]

Hi Savjee! I see in this video you said that you have fix the problem about minePendingTransactions() method in Github. But when I use your code in Github, it still have an error about reward like in your video. I still have to mine twice so that I could have receive the coin??? Why I can't reward the coin in the first time mining?

[@g_pazzini]

it's not an error... at the first time mining, you processed those 2 initial transactions. you haven't got rewarded.... after 1st mining, you got a reward which is posted as "pending" transaction and it's not in the block yet. that's why you need to do 2nd mining to have it in the block.

[@shandonanderson3967]

Can we expect to see the other videos uploaded for this series?

[@simplyexplained]

Yes, but not in the immediate future. Sorry about that! But you can help make it faster. Checkout the code on GitHub, make a pull request with new features and I could make a new video about it (and give you full credit ofcourse)

[@yuefeima6201]

great videos, thanks

[@williamokano]

Hi Savjee, but why not instead of leaving the balance of the miner to the next block you can't auto insert this transaction into the pending transactions plus setting a new property called "minedBy" to show that the miner really put some efforts into the mining? With this you can ensure that the token will be "instantly" transfered and anyone that can check the chain can build correctly the miners balance.

[@simplyexplained]

Sure, you could put the mining reward in the same block. However there is no need to add the "minedBy" property. You know who mined the block by checking where the mining reward went to ;)

[@ringoyip0901]

This is amazing! The only question I have is: once a pending transaction has been resolved, will it get deleted? Do we need to create a method for deleting a resolved pending transaction?

[@simplyexplained]

When a transaction is added to a block, we don't have to keep it in the pending transactions. The code does this by redefining the pendingTransactions array

[@j8577798yt]

Very good!!!

[@softtech5630]

Hay un error en el codigo de muestra que calcula el Hash porque está así: calculateHash() { return SHA256(this.index + this.timestamp + JSON.stringify(this.data)+ this.nonce).toString(); } Y DEBE QUEDAR ASI: calculateHash() { return SHA256(this.previousHash + this.timestamp + JSON.stringify(this.transactions) + this.nonce).toString(); }

[@rliy001]

In a"real blockchain", does it really keep adding the mining reward to the pending transactions list; and then another miner has to mine that transaction? Wouldn't this create an endless cycle of rewards, which of cause keeps introducing new bitcoins to the system. What I thought happens when someone mines a block is that the mining reward is added to the same block that just got mined. Is that right?

[@rja_live]

One block keeps many transactions, so it can includes one more transaction to reward previous miner