Ethereum-Name-Service.md

The Ethereum Name Service

Background

When web initially started the only way you could explore information on the web was by entering in its IP address. After that the concept of DNS was introduced which helped us to link a domain name to an IP address.

So whenever you type learnweb3.io, DNS takes care of translating it to the respective IP which is what the computer finally understands.

What is ENS?

ENS stands for The Ethereum Name Service and it behaves very similar to how DNS behaves in the web2 space. As we all know that Ethereum has long addresses which are hard to remember or type. ENS solves this issue by translating these wallet addresses, hashes etc into readable domains which are then saved on Ethereum blockchain.

The best part about ENS is unlike DNS servers which are centralized, ENS works with the help of a smart contract which is censorship resistant. So now when you are sending your wallet address to someone which looks like 0x1234huiahi.... you can actually send them tom.eth and the ENS would figure out that tom.eth is actually equal to your wallet address (0x1234huiahi....)

Additionally, ENS extends beyond just mapping wallet addresses to human-readable names. You can actually attach a profile picture, a description, social media links, as well as any custom types of data you'd want to attach.

Requirements

It's time to build something where we can use ENS. We will develop a website which can display the ENS for an address if it has one.

Let's gooo 🚀

Setup

First let's get an ENS name for your address, start by opening up https://app.ens.domains/

Make sure when you open the website, your MetaMask is connected to the Goerli Testnet and it has some Goerli Ether

Search for an ENS domain name, any name you like, as long as it is available!. Click on Available

Then click on Request To Register

When the progress bar enters the 3rd step, Click Register

Then after the progress bar finishes click on Set As Primary ENS Name

From the dropdown then select the ENS name you just created

Click Save

Now you have an ENS registered to your address on Goerli. Awesome, You did it ❤️

Website

To develop the website we will use React and Next Js. React is a javascript framework used to make websites and Next.js is a React framework that also allows writing backend APIs code along with the frontend, so you don't need two separate frontend and backend services. First, You will need to create a new next app. Your folder structure should look something like

- ENS
    - my-app

To create this next-app, in the terminal point to ENS folder and type

npx create-next-app@latest

and press enter for all the questions

Now to run the app, execute these commands in the terminal

cd my-app
npm run dev

Now go to http://localhost:3000, your app should be running 🤘

Let's install the Web3Modal library. Web3Modal is an easy to use library to help developers easily allow their users to connect to your dApps with all sorts of different wallets. By default Web3Modal Library supports injected providers like (Metamask, Dapper, Gnosis Safe, Frame, Web3 Browsers, etc) and WalletConnect, You can also easily configure the library to support Portis, Fortmatic, Squarelink, Torus, Authereum, D'CENT Wallet and Arkane. Open up a terminal pointing atmy-app directory and execute this command

npm install web3modal

In the same terminal also install ethers.js

Note : We install v5 specifically since the new v6 has breaking changes to the code.

npm install ethers@5

In your my-app/public folder, download this image and rename it to learnweb3punks.png

Now go to the styles folder and replace all the contents of Home.module.css file with the following code, this would add some styling to your dapp:

.main {
  min-height: 90vh;
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  font-family: "Courier New", Courier, monospace;
}

.footer {
  display: flex;
  padding: 2rem 0;
  border-top: 1px solid #eaeaea;
  justify-content: center;
  align-items: center;
}

.image {
  width: 70%;
  height: 50%;
  margin-left: 20%;
}

.title {
  font-size: 2rem;
  margin: 2rem 0;
}

.description {
  line-height: 1;
  margin: 2rem 0;
  font-size: 1.2rem;
}

.button {
  border-radius: 4px;
  background-color: blue;
  border: none;
  color: #ffffff;
  font-size: 15px;
  padding: 20px;
  width: 200px;
  cursor: pointer;
  margin-bottom: 2%;
}
@media (max-width: 1000px) {
  .main {
    width: 100%;
    flex-direction: column;
    justify-content: center;
    align-items: center;
  }
}

Open your index.js file under the pages folder and paste the following code, explanation of the code can be found in the comments.

import Head from "next/head";
import styles from "../styles/Home.module.css";
import Web3Modal from "web3modal";
import { ethers, providers } from "ethers";
import { useEffect, useRef, useState } from "react";

export default function Home() {
  // walletConnected keep track of whether the user's wallet is connected or not
  const [walletConnected, setWalletConnected] = useState(false);
  // Create a reference to the Web3 Modal (used for connecting to Metamask) which persists as long as the page is open
  const web3ModalRef = useRef();
  // ENS
  const [ens, setENS] = useState("");
  // Save the address of the currently connected account
  const [address, setAddress] = useState("");

  /**
   * Sets the ENS, if the current connected address has an associated ENS or else it sets
   * the address of the connected account
   */
  const setENSOrAddress = async (address, web3Provider) => {
    // Lookup the ENS related to the given address
    var _ens = await web3Provider.lookupAddress(address);
    // If the address has an ENS set the ENS or else just set the address
    if (_ens) {
      setENS(_ens);
    } else {
      setAddress(address);
    }
  };

  /**
   * A `Provider` is needed to interact with the blockchain - reading transactions, reading balances, reading state, etc.
   *
   * A `Signer` is a special type of Provider used in case a `write` transaction needs to be made to the blockchain, which involves the connected account
   * needing to make a digital signature to authorize the transaction being sent. Metamask exposes a Signer API to allow your website to
   * request signatures from the user using Signer functions.
   */
  const getProviderOrSigner = async () => {
    // Connect to Metamask
    // Since we store `web3Modal` as a reference, we need to access the `current` value to get access to the underlying object
    const provider = await web3ModalRef.current.connect();
    const web3Provider = new providers.Web3Provider(provider);

    // If user is not connected to the Goerli network, let them know and throw an error
    const { chainId } = await web3Provider.getNetwork();
    if (chainId !== 5) {
      window.alert("Change the network to Goerli");
      throw new Error("Change network to Goerli");
    }
    const signer = web3Provider.getSigner();
    // Get the address associated to the signer which is connected to  MetaMask
    const address = await signer.getAddress();
    // Calls the function to set the ENS or Address
    await setENSOrAddress(address, web3Provider);
    return signer;
  };

  /*
    connectWallet: Connects the MetaMask wallet
  */
  const connectWallet = async () => {
    try {
      // Get the provider from web3Modal, which in our case is MetaMask
      // When used for the first time, it prompts the user to connect their wallet
      await getProviderOrSigner(true);
      setWalletConnected(true);
    } catch (err) {
      console.error(err);
    }
  };

  /*
    renderButton: Returns a button based on the state of the dapp
  */
  const renderButton = () => {
    if (walletConnected) {
      <div>Wallet connected</div>;
    } else {
      return (
        <button onClick={connectWallet} className={styles.button}>
          Connect your wallet
        </button>
      );
    }
  };

  // useEffects are used to react to changes in state of the website
  // The array at the end of function call represents what state changes will trigger this effect
  // In this case, whenever the value of `walletConnected` changes - this effect will be called
  useEffect(() => {
    // if wallet is not connected, create a new instance of Web3Modal and connect the MetaMask wallet
    if (!walletConnected) {
      // Assign the Web3Modal class to the reference object by setting it's `current` value
      // The `current` value is persisted throughout as long as this page is open
      web3ModalRef.current = new Web3Modal({
        network: "goerli",
        providerOptions: {},
        disableInjectedProvider: false,
      });
      connectWallet();
    }
  }, [walletConnected]);

  return (
    <div>
      <Head>
        <title>ENS Dapp</title>
        <meta name="description" content="ENS-Dapp" />
        <link rel="icon" href="/favicon.ico" />
      </Head>
      <div className={styles.main}>
        <div>
          <h1 className={styles.title}>
            Welcome to LearnWeb3 Punks {ens ? ens : address}!
          </h1>
          <div className={styles.description}>
            {/* Using HTML Entities for the apostrophe */}
            It&#39;s an NFT collection for LearnWeb3 Punks.
          </div>
          {renderButton()}
        </div>
        <div>
          <img className={styles.image} src="./learnweb3punks.png" />
        </div>
      </div>

      <footer className={styles.footer}>
        Made with &#10084; by LearnWeb3 Punks
      </footer>
    </div>
  );
}

Now in your terminal which is pointing to my-app folder, execute

npm run dev

Your ENS dapp should now work without errors 🚀

Push to github

Make sure before proceeding you have pushed all your code to github :)

Deploying your dApp

We will now deploy your dApp, so that everyone can see your website and you can share it with all of your LearnWeb3 DAO friends.

• Go to Vercel and sign in with your GitHub
• Then click on New Project button and then select your ENS dApp repo
• 
• When configuring your new project, Vercel will allow you to customize your Root Directory
• Click Edit next to Root Directory and set it to my-app
• Select the Framework as Next.js
• Click Deploy
• Now you can see your deployed website by going to your dashboard, selecting your project, and copying the URL from there!

---

To pass the skill test for this level, input YOUR address you used to buy the ENS domain from in the verification box.

Share your website on Discord :D and as usual, feel free to ask any questions!