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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta
name="viewport"
content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no"
/>
<title>Budowanie frontendów dla aplikacji Ethereum</title>
<link rel="stylesheet" href="dist/reset.css" />
<link rel="stylesheet" href="dist/reveal.css" />
<link rel="stylesheet" href="dist/theme/black.css" />
<!-- Theme used for syntax highlighted code -->
<link rel="stylesheet" href="plugin/highlight/monokai.css" />
</head>
<body>
<div class="reveal">
<div class="slides">
<section>
<h1 class="r-fit-text">
Budowanie frontendów <br />dla aplikacji Ethereum
</h1>
<p class="fragment">Co wiedzieć, zanim zaczniesz web3</p>
<p class="fragment">w 6 księgach zapisane</p>
</section>
<section>
<h3>Księgi</h3>
<ul class="fragment">
<li>Blockchain dla nerdów</li>
<li>Dapps</li>
<li>Testy</li>
<li>Wyzwania</li>
<li>Tokeny ERC-20</li>
<li>Przegląd projektów</li>
</ul>
</section>
<section>
<ul>
<li>blockchain</li>
<li class="fragment">crypto</li>
<li class="fragment">web3</li>
</ul>
</section>
<section>
<h3>Pytania</h3>
<ul>
<li class="fragment">Czy wiesz, co to web3?</li>
<li class="fragment">Czy uczysz się czegoś o web3?</li>
<li class="fragment">Czy robisz już coś w web3?</li>
<li class="fragment">
Czy uważasz, że warto inwestować czas na naukę?
</li>
</ul>
</section>
<section>
<p class="r-fit-text">10 miesięcy</p>
<p class="r-fit-text fragment">Od rozpoczęcia pracy z blockchain</p>
</section>
<section>
<p class="r-fit-text">web2 vs web3</p>
<p class="r-fit-text fragment">o różnicach, o tradeoffach</p>
</section>
<section>
<h3>Kim jestem, co robię…</h3>
<ul>
<li class="fragment">Mam na imię Kuba</li>
<li class="fragment">Prowadzę kanał <a href="https://www.youtube.com/c/jsdzem" target="_blank">JS Dżem</a></li>
<li class="fragment">+5 lat doświadczenia na frontendzie</li>
<li class="fragment">TypeScript</li>
<li class="fragment">React + Redux</li>
</ul>
</section>
<section>
<img data-src="https://jsdzem.pl/wp-content/uploads/2022/06/js-dzem-yt.png" alt="JS Dżem on YouTube" />
</section>
<!-- PART ONE -->
<section>
<h2>Księga pierwsza</h2>
<p>Blockchain dla nerdów</p>
</section>
<section>
<h3>Po co Ci blockchain?</h3>
<ul>
<li class="fragment">
Zaufana trzecia strona jest niezbędna, aby zapobiec podwójnemu
wydaniu tych samych środków
</li>
<li class="fragment">
Dowód kryptograficzny zamiast centralnego zaufania
</li>
<li class="fragment">Zaufanie do sieci, a nie do instytucji</li>
</ul>
</section>
<section>
<figure>
<blockquote>
<p>
“Z punktu widzenia tworzenia oprogramowania jedną z największych
zmian wydaje się zakwestionowanie tradycyjnej, centralnej bazy
danych. Musimy więc dogłębnie przemyśleć w jaki sposób
blockchain zmusza nas do przemyślenia istniejących konstrukcji
baz danych.”
</p>
</blockquote>
<figcaption>
—William Mougayar, Vitalik Buterin,<br />
<cite>The Business Blockchain</cite>
</figcaption>
</figure>
</section>
<section>
<img data-src="https://jsdzem.pl/wp-content/uploads/2022/06/kielbus-wyjasnia-krypto.png" alt="Rafał Kiełbus wyjaśnia krypto" />
</section>
<section>
<h3>Dlaczego dotychczas nie płaciłeś PRZEZ INTERNET?</h3>
<p class="fragment">Co to w ogóle znaczy "płacić przez internet"?</p>
</section>
<section>
<h3>Wire transfer? 😂</h3>
<img style="max-height: 50vh;" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/wire.jpg" alt="Wire" />
</section>
<section>
<img data-src="https://jsdzem.pl/wp-content/uploads/2022/06/p2p-vs-banks.png" alt="p2p vs banks" />
</section>
<section>
<div style="display: flex; justify-content: center;">
<blockquote class="twitter-tweet"><p lang="pl" dir="ltr">Ktoś przelał 329 mln dolców w <a href="https://twitter.com/hashtag/Bitcoin?src=hash&ref_src=twsrc%5Etfw">#Bitcoin</a> i zapłacił opłatę w wysokości 0,12 dolara.<br><br>To jest opłata za transakcję w wysokości 0,0000000003644%.<br><br>Bez blokad, bez pośredników, bez banków. <a href="https://twitter.com/hashtag/kryptowaluty?src=hash&ref_src=twsrc%5Etfw">#kryptowaluty</a> <a href="https://twitter.com/hashtag/kryptoekipa?src=hash&ref_src=twsrc%5Etfw">#kryptoekipa</a> <a href="https://twitter.com/hashtag/finanse?src=hash&ref_src=twsrc%5Etfw">#finanse</a> <a href="https://t.co/b76E2gBOjN">pic.twitter.com/b76E2gBOjN</a></p>— K.O Kryptowaluty (@KO_Kryptowaluty) <a href="https://twitter.com/KO_Kryptowaluty/status/1531139338943143937?ref_src=twsrc%5Etfw">May 30, 2022</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
</div>
</section>
<section>
<h3>publiczny i (ale) anonimowy</h3>
<ul>
<li class="fragment">
Transakcje są publiczne (id)
</li>
<li class="fragment">
Jesteś anonimowy, dopóki nie znają twojego adresu 🧵
</li>
<li class="fragment">
Transparentność
<ul>
<li class="fragment">
Pewność że moje pieniądze nigdzie nie znikną
</li>
<li class="fragment">
Łatwość wyśledzenia przestępców
</li>
</ul>
</li>
</ul>
</section>
<section>
<h3 class="r-fit-text">Open source</h3>
</section>
<!-- PART TWO -->
<section>
<h2>Księga druga</h2>
<p>Dapps</p>
</section>
<section>
<h3>Disclaimer</h3>
<ul>
<li class="fragment">only MetaMask wallet 🦊</li>
<li class="fragment">⚛️ React + optional Redux</li>
<li class="fragment"><a href="https://docs.ethers.io/v5/" target="_blank">ethers.js</a></li>
<li class="fragment">no high level solutions (<a href="https://usedapp.io/" target="_blank">useDapp</a>, <a href="https://trufflesuite.com/drizzle/" target="_blank">Drizzle</a>)</li>
<li class="fragment">🙅♂️ no Solidity, no smart contracts</li>
<li class="fragment">only ERC-20, no NFTs</li>
</ul>
</section>
<section>
<div style="display: flex; justify-content: center;">
<blockquote class="twitter-tweet"><p lang="en" dir="ltr">Remember that you should always test your dapp with at least one non-metamask wallet (eg. Brave, Status browser). Make sure your dapp conforms to ethereum standards, and not just to accidental properties of one particular wallet!</p>— vitalik.eth (@VitalikButerin) <a href="https://twitter.com/VitalikButerin/status/1531771109602799617?ref_src=twsrc%5Etfw">May 31, 2022</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
</div>
</section>
<section>
<h3>Dlaczego Ethereum?</h3>
<img style="max-height: 50vh;" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/blckch-devs-chart.webp" alt="Infura" />
<a href="https://a16zcrypto.com/state-of-crypto-report-a16z-2022/" target="_blank">https://a16zcrypto.com/state-of-crypto-report-a16z-2022/</a>
</section>
<section>
<h3>
Decentralized front-end
</h3>
<ul>
<li class="fragment">
no backend (❌CRUD, ❌REST, ❌HTTP)
</li>
<li class="fragment">no HTTP requests (❌fetch, ❌axios)</li>
<li class="fragment">
Talks directly to blockchain ✅
</li>
<li class="fragment">
blockchain node (read) ✅
</li>
<li class="fragment">
wallet (read, write) ✅
</li>
<li class="fragment">no matter where deployed ✅</li>
<li class="fragment">IPFS ✅</li>
</ul>
</section>
<section>
<p>Wszystko jest to samo</p>
<p style="font-size: 5em;">😎</p>
<p class="fragment">tylko łączysz się z węzłem sieci Ethereum<br /> zamiast serwerem HTTP.</p>
</section>
<section>
<div style="display: flex; justify-content: center;">
<blockquote class="twitter-tweet"><p lang="en" dir="ltr">BREAKING: Web2 and Web3 are the same damn thing.</p>— JackForge.eth (@TheJackForge) <a href="https://twitter.com/TheJackForge/status/1524603955489255424?ref_src=twsrc%5Etfw">May 12, 2022</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
</div>
</section>
<section>
<p>Nie wyklucza to, że pewne dane<br/> mogą być pobierane<br/> z centralizowanych serwerów</p>
<p style="font-size: 2em;">🗯</p>
<ul>
<li class="fragment">optymalizacji kosztów</li>
<li class="fragment">dane wtórne</li>
<li class="fragment">mało istotne dane</li>
<li class="fragment">niewraliwe</li>
</ul>
</section>
<section>
<div style="display: flex; justify-content: center;">
<blockquote class="twitter-tweet"><p lang="en" dir="ltr">Re: non-financial blockchain use cases. <a href="https://t.co/lYZFprXAry">pic.twitter.com/lYZFprXAry</a></p>— vitalik.eth (@VitalikButerin) <a href="https://twitter.com/VitalikButerin/status/1530268923848839173?ref_src=twsrc%5Etfw">May 27, 2022</a></blockquote>
<script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
</div>
</section>
<!-- TODO -->
<section>
<h3>How to get connected to the blockchain?</h3>
<ol>
<li class="fragment">
Get smartcontract address and its ABI (Application Binary
Interface)
</li>
<li class="fragment">Initialize a provider (wallet, node)</li>
<li class="fragment">
Create a smartcontract class instance - SM abstraction in JS
</li>
<li class="fragment">
Call a contract method to get or set data in a blockchain
</li>
<li class="fragment">
You can also Listen to the events on smartcontract (pooling, web
sockets)
</li>
</ol>
</section>
<section>
<h3>Smartcontract address & ABI</h3>
<p class="fragment">Czy ABI to takie inne API?</p>
</section>
<section>
<p>❌ Nie pobieram ABI z zewnętrznych źródeł</p>
<p class="fragment">✅ Zawsze hardkoduję adresy smartkontraktów</p>
<p class="fragment" style="font-size: 3em;">dlaczego ❓</p>
</section>
<section>
<h3>Connecting to a node</h3>
<ul>
<li class="fragment">Why do I need a node?</li>
<li class="fragment">When to use my own node (Infura, Alchemy)?</li>
<li class="fragment">
Can any front-end connect to any smart contract?
</li>
</ul>
</section>
<section>
<h3>Node providers</h3>
<div style="display: flex;">
<div>
<a href="https://infura.io/" target="_blank">Infura</a>
<img data-src="https://jsdzem.pl/wp-content/uploads/2022/06/infura.png" alt="Infura" />
</div>
<div>
<a href="https://www.alchemy.com/" target="_blank">Alchemy</a>
<img data-src="https://jsdzem.pl/wp-content/uploads/2022/06/alchemy.png" alt="Alchemy" />
</div>
</div>
</section>
<section>
<h3>Platforms</h3>
<div style="display: flex; justify-content: center;">
<blockquote class="twitter-tweet"><p lang="en" dir="ltr">Last week we had a great workshop on how <a href="https://twitter.com/MoralisWeb3?ref_src=twsrc%5Etfw">@MoralisWeb3</a> saves developers<br>time and money to ship scalable & robust Dapps - with <a href="https://twitter.com/Shiv_24561?ref_src=twsrc%5Etfw">@Shiv_24561</a> & <a href="https://twitter.com/YSoenggoro?ref_src=twsrc%5Etfw">@YSoenggoro</a> <a href="https://t.co/D5p4Eei5pN">pic.twitter.com/D5p4Eei5pN</a></p>— lecryptofellowship (@lecryptofellow) <a href="https://twitter.com/lecryptofellow/status/1530219416536883201?ref_src=twsrc%5Etfw">May 27, 2022</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
</div>
</section>
<section>
<h3>Using smart contract methods</h3>
<ul>
<li class="fragment">type of methods: read and write</li>
<li class="fragment">no put/patch and delete substitutes (blockchain design)</li>
</ul>
</section>
<section>
<h3 class="r-fit-text">READ methods</h3>
<ul>
<li class="fragment">free 🆓 you don't pay ETH for gas</li>
<li class="fragment">no wallet required, shared node is enough</li>
<li class="fragment">() ⇒ Promise<Result></li>
<li class="fragment">no event emitted</li>
</ul>
</section>
<section>
<h3 class="r-fit-text">WRITE methods</h3>
<ul>
<li class="fragment">cost you to pay for gas</li>
<li class="fragment">connected wallet required</li>
<li class="fragment">() ⇒ Promise<{ wait: () ⇒ Promise<Receipt> }></li>
<li class="fragment">can emit events</li>
<li class="fragment">one SC can contain read and write methods</li>
</ul>
</section>
<section>
<p>You have to pay for gas, <br/> even if transaction failed</p>
<img style="max-height: 30vh;" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/pay-the-bill.png" alt="pay the bill" />
<p class="fragment">👮♂️ DDos protection</p>
</section>
<section>
<h3>Jeśli to możliwe,<br /> łącz się przez wallet</h3>
<div class="r-stack">
<img class="fragment" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/read-write-1.png" alt="Read and write 1" />
<img class="fragment" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/read-write-2.png" alt="Read and write 2" />
</div>
<a class="fragment" href="https://www.youtube.com/watch?v=kDan1tp4hpA" target="_blank">https://www.youtube.com/watch?v=kDan1tp4hpA</a>
</section>
<!-- PART THREE -->
<section>
<h2>Księga trzecia</h2>
<p>Testy</p>
</section>
<section>
<h3>Unit test</h3>
<ul>
<li class="fragment">smart contracts covered on Solidity level</li>
<li class="fragment">there's no difference if you use web3</li>
<li class="fragment">unit test should be blockchain unaware, detached</li>
<li class="fragment">if you use React, just test components or functions</li>
</ul>
</section>
<section>
<h3>E2E tests</h3>
<ul>
<li class="fragment">Cypress + MetaMask = Synpress<br />
<a>https://github.com/Synthetixio/synpress</a></li>
<li class="fragment">manual testing</li>
</ul>
</section>
<section>
<h3>Dev tools</h3>
<p>MetaMask requests<br /> doesn't affect network tab<br /> in browser dev tools</p>
<ul>
<li class="fragment">no throttling</li>
<li class="fragment">browser doesn't treat SC call like HTTP request</li>
<li class="fragment">MetaMask is a black box</li>
</ul>
</section>
<section>
<h3>Wallet is a blackbox</h3>
<ul>
<li class="fragment">MetaMask does not allow to disconnect app 🤥</li>
<li class="fragment">Access only via methods specified in <a href="https://docs.metamask.io/guide/ethereum-provider.html#methods" target="_blank">MetaMask API</a></li>
<li class="fragment"><a href="https://docs.metamask.io/guide/rpc-api.html#wallet-watchasset" target="_blank">wallet_watchAsset</a> case</li>
</ul>
</section>
<section>
<h3>Integration tests</h3>
<ul>
<li class="fragment"><a href="https://testing-library.com/">@testing-library</a></li>
<li class="fragment">implementation agnostic</li>
<li class="fragment">how front-end deals with errors</li>
<li class="fragment">only services are mocked</li>
</ul>
</section>
<section>
<h3>Services</h3>
<div class="r-stack">
<img class="fragment" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/services-1.png" alt="Services" />
<img class="fragment" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/services-2.png" alt="Services" />
<img class="fragment" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/services-3.png" alt="Services" />
</div>
</section>
<section>
<h2>Environments</h2>
<img class="fragment" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/environments.png" alt="Environments" />
</section>
<!-- PART FOUR -->
<section>
<h2>Księga czwarta</h2>
<p>Wyzwania</p>
</section>
<section>
<h3>Arytmetyka na frontendzie</h3>
<ul>
<li class="fragment">biblioteka <a href="https://github.com/alexbardas/bignumber.js" target="_blank">BigNumber</a></li>
<li class="fragment">nawet do 27 miejsc po przecinku</li>
<li class="fragment">ewentualnie liczby w stringach</li>
</ul>
</section>
<section>
<h3>Primitive obsession</h3>
</section>
<section>
<pre><code>
export type LiquidationDepositAmount = string & {
type: 'LIQUIDATION_DEPOSIT_AMOUNT';
};
export type OpeningFeeRate = string & {
type: 'OPENING_FEE_RATE';
};
export type OpeningFeeAmount = BigNumber & {
type: 'OPENING_FEE_AMOUNT';
};
</code></pre>
</section>
<section>
<h3>Data received from blockchain to JS</h3>
<ul>
<li class="fragment">fake Array - actually it has fields like object</li>
<li class="fragment">depends on provided ABI format</li>
<li class="fragment">TypeScript typings rather expect Array. If you want to read it as object, you need to assert your own type.</li>
<li class="fragment">example: getMySwaps</li>
</ul>
</section>
<section>
<h3>Non-serializable data</h3>
<img class="fragment" data-src="https://jsdzem.pl/wp-content/uploads/2022/06/redux-non-serializable.png" alt="Non-serializable data" />
</section>
<section>
<h3>Non-serializable data</h3>
<ul>
<li class="fragment">BigNumber is non-serializable - redux, localStorage 😞</li>
<li class="fragment">ethers.js returns BigNumber instance for uint256 and other number format</li>
<li class="fragment">UI wants text representation</li>
<li class="fragment">number string?</li>
<li class="fragment">What if I have many calcs and conversion?</li>
<li class="fragment">Referential equality matters, no value equality - React 🙈</li>
</ul>
</section>
<section>
<h3>Redux architecture case</h3>
<p class="fragment" style="max-width: 60vw; margin: 0 auto;">
<span class="fragment">service</span>
<span class="fragment">➡️ BN</span>
<span class="fragment">➡️ string</span>
<span class="fragment">➡️ reducer</span>
<span class="fragment">➡️ store</span>
<span class="fragment">➡️ selector (BN for calcs)</span>
<span class="fragment">➡️ component</span>
<span class="fragment">➡️ (BN)</span>
</p>
</section>
<section>
<h3>Inaczej są wyrzucane błędy przez metamask a inaczej przez Infurę</h3>
<pre><code>
const getErrorCode = (error: unknown): UserErrorCode => {
if (!(error instanceof Error)) {
/**
* If contract method is called via Metamask wallet
* then error is non-Error type
* and has different structure than thrown via public RCP provider
*/
if (isErrorFromWallet(error)) {
const code = getErrorFromWalletCode(error);
if (code) {
return code;
}
}
/**
* Non contract related errors
* Metamask's errors are non-Error type
*/
if (isMetamaskError(error)) {
const code = getMetamaskErrorCode(error);
if (code) {
return code;
}
}
return 'UNEXPECTED_ERROR';
}
/**
* If contract method is called via Public RCP provider
* then error is Error type
* and has different structure than thrown via Metamask wallet
*/
if (isErrorFromPublicRcp(error)) {
const code = getErrorFromPublicRcpCode(error);
if (code) {
return code;
}
}
if (error instanceof TypeError) {
return 'UNEXPECTED_ERROR';
}
return 'UNEXPECTED_ERROR';
};
</code></pre>
</section>
<section>
<h3>Error logging</h3>
<ul>
<li class="fragment">No server logs</li>
<li class="fragment">No idea what's on client side</li>
</ul>
</section>
<section>
<p>It's a good practice to log errors anyway,<br />regardless it's either web3 or web2</p>
<ul>
<li><a href="https://sentry.io/welcome/">sentry.io</a></li>
<li><a href="https://logrocket.com/">Log Rocket</a></li>
</ul>
</section>
<section>
<h3>TypeScript vs Smart Contract (ABI)</h3>
<ul>
<li class="fragment"><a href="https://github.com/dethcrypto/TypeChain" target="_blank">Typechain</a></li>
<li class="fragment">Custom class interface - code editor: UserAsset.ts</li>
</ul>
</section>
<section>
<h3>Czytanie danych z logów i eventów</h3>
</section>
<!-- PART FIVE -->
<section>
<h2>Księga piąta</h2>
<p>Tokeny ERC-20</p>
</section>
<section>
<h3>Smart Contracs interactions</h3>
<p class="r-fit-text">ERC20 standard</p>
<p>
<a href="https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/IERC20.sol">https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/IERC20.sol</a>
</p>
</section>
<section>
<h3>UX vs security</h3>
<p class="r-fit-text">unlimited allowance</p>
<p>
<a href="https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/IERC20.sol">https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/IERC20.sol</a>
</p>
</section>
<!-- PART SIX -->
<section>
<h2>Księga szósta</h2>
<p>Przegląd projektów</p>
<ul>
<li class="fragment"><a href="https://uniswap.org/">Uniswap</a></li>
<li class="fragment"><a href="https://aave.com/">Aave</a></li>
<li class="fragment"><a href="https://pancakeswap.finance/">Pancake Swap</a></li>
</ul>
</section>
<section>
<h3>Web3 Devs PL</h3>
<a href="https://web3devs.pl/">https://web3devs.pl/</a>
</section>
<section>
<div style="display: flex; justify-content: center;">
<blockquote class="twitter-tweet"><p lang="en" dir="ltr">Learn Web3 -> get paid.<br><br>10 best resources to kickstart your Web3 development journey in 2022.<br><br>A Thread ↓</p>— Vitto Rivabella | 0xvitto.eth (@VittoStack) <a href="https://twitter.com/VittoStack/status/1524044099006967814?ref_src=twsrc%5Etfw">May 10, 2022</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
</div>
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