While Bitcoin is now part of the common vocabulary, there is a lot of talks recently about a concept that is still a little hard to understand to the average developer. The concept of a decentralized application (Dapp for short or Web3 app) is starting to gather a lot of attention on the web. Many people are starting to label themselves as "Web3 developers" and people are wondering what is the difference between a Web3 app and a traditional web app.
If we elevate ourselves above the crypto hype, we can start to ask ourselves relevant questions. How do we host and deploy those apps? How do we use them? How do we use them in the browser? The good news is that from a coding perspective, the answer is clear: a Web3 app is still calling modules, APIs and libraries. It is still using the same JavaScript language as we are used to.
In short, a Web3 app is still a web app, but it follows a set of philosophies: anonymity, security and privacy. Let's dive into the details to understand some of those basic concepts! In this post, we will build a simple Web3 app that uses the Metamask browser extension. We will use the Ethereum blockchain to store data and interact with the blockchain.
This is not a complete app, but it is a good starting point to understand the basics.
We will start with a simple Next.js app. Let's start by creating a new project:
yarn create next-app --typescript
cd next-app
Once this is done, we will need to install the metamask extension. Metamask is a simple extension that allows you to interact with the Ethereum blockchain and create wallets for it. Please follow the instructions on their website. Once the Metamask is installed, we can proceed and create a wallet. Follow this great post for more details on how to do it.
In order to interact with Metamask, we need to connect it to the app. While we are using Next.js, Metamask works by injecting a new property on the Window object. This means that we will not be able to use any of the Metamask features on the server-side. This means that most features of a web3 app are client-side. The interesting part is that we can use the Metamask API to interact with the blockchain. The blockchain then provides a backend to our application. We'll explore in further posts how to interact with the blockchain.
For now, let's install some packages to make it easier to interact with Metamask. We will also create a simple Hook that will allow us to interact with the Metamask API.
yarn add @metamask/detect-provider @metamask/onboarding @metamask/providers
touch hooks/use-metamask.tsx
Once this is done, make sure you have this content in your
hooks/use-metamask.tsx file:
import React from 'react';
import MetaMaskOnboarding from '@metamask/onboarding';
import { MetaMaskInpageProvider } from '@metamask/providers';
import detectEthereumProvider from '@metamask/detect-provider';
export const useMetamask = () => {
const [account, setAccount] = React.useState<string>('');
const [ethereum, setEthereum] = React.useState<MetaMaskInpageProvider | null>(null);
const onboarding = React.useRef<MetaMaskOnboarding>();
function handleOnboarding() {
if (MetaMaskOnboarding.isMetaMaskInstalled()) {
ethereum?.request({ method: 'eth_requestAccounts' }).then((accounts) => {
console.log(accounts);
});
} else {
onboarding.current?.startOnboarding();
}
}
function handleAccountChange(accounts?: string[]) {
if (accounts && accounts.length > 0) {
setAccount(accounts[0]);
return;
}
if (accounts && accounts.length === 0) {
setAccount('');
return;
}
if (ethereum?.selectedAddress) {
setAccount(ethereum?.selectedAddress);
return;
}
}
React.useEffect(() => {
if (!onboarding.current) {
onboarding.current = new MetaMaskOnboarding();
}
detectEthereumProvider().then((provider) => {
if (!provider) {
return;
}
setEthereum(provider as MetaMaskInpageProvider);
});
}, []);
React.useEffect(() => {
if (ethereum) {
handleAccountChange();
ethereum?.on('accountsChanged', handleAccountChange);
}
}, [ethereum]);
return { ethereum, account, handleOnboarding };
};
This hook creates a way for us to watch which wallets are currently in use in
the Metamask extension. We will use this to determine if we need to show the
onboarding screen or not. Once we are done adding it to our application, let's
modify the content of the pages/index.tsx file to use it:
import type { NextPage } from 'next';
import Head from 'next/head';
import { useMetamask } from '../hooks/use-metamask';
const Home: NextPage = () => {
const { account, handleOnboarding } = useMetamask();
return (
<div>
<Head>
<title>Create Next App</title>
<meta name="description" content="Generated by create next app" />
<link rel="icon" href="/favicon.ico" />
</Head>
{account.length === 0 ? <button onClick={handleOnboarding}>Connect</button> : account}
</div>
);
};
export default Home;
This simple code just checks if the user has a wallet connected to the Metamask extension. If they don't have one, it will prompt them to connect one or install the extension. If they do have one, it will display the address of the wallet.
Obviously, this is not a complete app, but it is a good starting point to understand the basics.
If you wish to test out the app, you can run the following command and navigate to localhost:3000.
yarn dev
The next step is to deploy the app to Vercel. We will use the Vercel CLI. The good news is that you can deploy the app to Vercel in a few minutes. Nothing changes in deploying the frontend part of a Web3 app. The only thing that changes is the backend part which is essentially smart contracts and a blockchain!
Let's start by connecting to our Vercel account:
vercel login
Once this is done, we can deploy the app to Vercel.
vercel deploy
Since this is a next.js app, nothing has changed in the deployment process! We can follow the steps in the deployment process to deploy the app to Vercel. We will end up with a new URL for our app. If we visit this URL, we should be able to interact with our Metamask wallet.
A simple Web3 app is now deployed to Vercel. The real difference for a frontend Web3 app is in the way we build it, not in the deployment. We will continue to explore the deployment process in the next post when we will cover how to deploy smart contracts to the blockchain. Web3 is an exciting new world and we can build great things with it once we start to understand the basics. Here is a recap:
@guibibeau on Twitter for any questions!