Building a Web3 application primarily involves connecting to a blockchain network, managing user wallets, and writing smart contracts. Ethereum is currently the most mainstream smart contract platform, Metamask serves as a popular wallet tool, making it easy for users to manage assets and sign transactions, while Solidity is the main programming language for Ethereum smart contracts. Below, I will guide you step by step to build a simple Web3 application from scratch.
Connecting to the Ethereum Network#
To interact with Ethereum, you first need to connect to an Ethereum node. The common way to do this is through the JavaScript libraries Web3.js or Ethers.js. Here, I recommend using Ethers.js, as its API is concise and easy to use.
`import { ethers } from "ethers";
const provider = new ethers.providers.Web3Provider(window.ethereum);`
This code will call the Metamask wallet installed in the browser and automatically connect to the Ethereum network currently selected by the user. When users visit for the first time, Metamask will pop up an authorization request, allowing your application to access the wallet address.
Managing Wallets with Metamask#
Metamask is not just a wallet; it is also an entry point for user identity. Through it, users can sign transactions and manage assets.
Request user authorization to access the wallet address:
`async function requestAccount() {
await window.ethereum.request({ method: 'eth_requestAccounts' });
}`
After calling this function, the user will see a Metamask popup to confirm the authorization. Once authorized successfully, you can obtain the user address through the provider:
`const signer = provider.getSigner();
const userAddress = await signer.getAddress();
console.log("Current user address:", userAddress);`
This completes the wallet connection and user identity retrieval.
Writing a Simple Solidity Smart Contract#
Solidity is the mainstream language for Ethereum smart contracts. Here’s a simple contract that stores a number:
`// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract SimpleStorage {
uint256 private storedData;
function set(uint256 x) public {
storedData = x;
}
function get() public view returns (uint256) {
return storedData;
}
}`
This contract has two functions: set to store a number and get to retrieve the number.
Deploying the Smart Contract#
To deploy the contract, you need a development environment, such as Remix IDE, or frameworks like Hardhat or Truffle. Here, I recommend using Remix for its simplicity.
- Open Remix IDE.
- Create a new file and paste the Solidity code above.
- Select the appropriate compiler version and click compile.
- Connect the Metamask wallet and select a test network (e.g., Goerli).
- Click deploy; Metamask will pop up a transaction confirmation. Confirm and wait for block confirmation.
After successful deployment, you will receive a contract address.
Calling the Smart Contract from the Frontend#
After deploying the contract, the frontend interacts with the contract using the contract address and ABI.
`const contractAddress = "your contract address";
const contractABI = [ /* ABI generated after Remix compilation */ ];
const contract = new ethers.Contract(contractAddress, contractABI, signer);
// Call the set function
async function setValue(value) {
const tx = await contract.set(value);
await tx.wait();
console.log("Storage successful");
}
// Call the get function
async function getValue() {
const value = await contract.get();
console.log("Current stored value:", value.toString());
}`
Calling setValue will initiate a transaction that the user needs to confirm in Metamask. Calling getValue is a read operation that does not require transaction fees.
Recommended Backup Domains for Domestic Users to Access Exchanges#
In cryptocurrency operations, accessing the official exchange website is common. Domestic users can use the backup domains provided by Hyperlink Navigation to ensure stable access:
These backup domains help users quickly access the latest official addresses of exchanges, avoiding access issues due to network fluctuations.
Summary#
The key to building a Web3 application is connecting to the Ethereum network, managing user wallets, and writing smart contracts. With Ethers.js and Metamask, the frontend can easily achieve wallet connection and transaction signing. Solidity smart contracts handle business logic and can be called after deployment to the test network. Domestic users can ensure smooth access during cryptocurrency operations by using the backup domains provided by Hyperlink Navigation. Mastering these basics makes Web3 application development easier, and hands-on practice is the best way to learn.