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Integrate Web3Auth with the Astar zkEVM Blockchain in JavaScript

While using the Web3Auth Web SDK, you get a EIP1193 provider, similar to the Metamask Provider. This provider can be used with libraries like web3.js, ethers.js etc. to make Astar zkEVM blockchain calls like getting the user's account, fetching balance, sign transaction, send transaction, read from and write to the smart contract, etc. We have highlighted a few here to get you started quickly on that.

Installation​

To interact with the zkEVM blockchain, you can use either library with Web3Auth.

npm install --save viem

Initializing Provider​

Using eip155 as chainNamespace while initializing web3auth will provide an EIP1193 compatible provider as web3auth.provider after successful authentication.

Getting the chainConfig​

const chainConfig = {
  chainNamespace: CHAIN_NAMESPACES.EIP155,
  chainId: "0xEC0", // hex of 3776
  rpcTarget: "https://rpc.startale.com/astar-zkevm",
  // Avoid using public rpcTarget in production.
  // Use services like Infura, Quicknode etc
  displayName: "Astar zkEVM",
  blockExplorerUrl: "https://astar-zkevm.explorer.startale.com/",
  ticker: "ETH",
  tickerName: "ETH",
  logo: "https://raw.githubusercontent.com/AstarNetwork/brand-assets/main/ASTARzkEVM_PortalIcons/100023_ASTARzkEVM_128x128_PortalIcon_ETH_v1aWEB.png",
};

Initializing and instantiating the Web3Auth SDK​

import { Web3Auth } from "@web3auth/modal";
import { EthereumPrivateKeyProvider } from "@web3auth/ethereum-provider";
import { WEB3AUTH_NETWORK } from "@web3auth/base";

const privateKeyProvider = new EthereumPrivateKeyProvider({
  config: { chainConfig: chainConfig },
});

const web3auth = new Web3Auth({
  // Get it from Web3Auth Dashboard
  clientId,
  web3AuthNetwork: WEB3AUTH_NETWORK.SAPPHIRE_MAINNET,
  privateKeyProvider,
});

Getting the Web3Auth provider​

After initializing Web3Auth, the next step is to initialize the provider and use it for your operations.

// Initialize for PnP Modal SDK
await web3auth.initModal();

// Trigger the login
await web3auth.connect();

// Get the provider
const provider = web3auth.provider;

// Continue using the `provider`

After logging in, the Web3Auth instance will provide you with information regarding the user that is logged in. This information is obtained directly from the JWT token and is not stored by Web3Auth. Therefore, this information can only be accessed through social logins after the user has logged into your application.

const user = await web3auth.getUserInfo(); // web3auth instance

Get Account and Balance​

const publicClient = createPublicClient({
  chain: mainnet, // for mainnet
  transport: custom(this.provider),
});

const walletClient = createWalletClient({
  chain: mainnet,
  transport: custom(this.provider),
});

// Get user's Ethereum public address
const address = await walletClient.getAddresses();

// Get user's balance in ether
const balance = await publicClient.getBalance({ address: address[0] });

Send Transaction​

/*
  Use code from the above Initializing Provider here
*/

const publicClient = createPublicClient({
  chain: mainnet, // for mainnet
  transport: custom(this.provider),
});

const walletClient = createWalletClient({
  chain: mainnet, // for mainnet
  transport: custom(this.provider),
});

// data for the transaction
const destination = "<ADDRESS>";
const amount = parseEther("0.0001");
const address = await this.getAccounts();

const address = await walletClient.getAddresses();

// Submit transaction to the blockchain
const hash = await walletClient.sendTransaction({
  account: address[0],
  to: destination,
  value: amount,
});

const receipt = await publicClient.waitForTransactionReceipt({ hash });

Sign Transaction​

/*
  Use code from the above Initializing Provider here
*/

const walletClient = createWalletClient({
  chain: mainnet, // for mainnet
  transport: custom(this.provider),
});

// data for the transaction
const destination = "<ADDRESS>";
const amount = parseEther("0.0001");
const address = await this.getAccounts();

const address = await walletClient.getAddresses();

// Prepare transaction
const request = await walletClient.prepareTransactionRequest({
  account: address[0],
  to: destination,
  value: amount,
});

// Sign transaction
const signature = await walletClient.signTransaction(request);

// Submit transaction to the blockchain
const hash = await walletClient.sendRawTransaction(signature);

Sign Message​

Personal Sign​

/*
  Use code from the above Initializing Provider here
*/

const publicClient = createPublicClient({
  chain: mainnet, // for mainnet
  transport: custom(this.provider),
});

const walletClient = createWalletClient({
  chain: mainnet, // for mainnet
  transport: custom(this.provider),
});

// data for signing
const address = await walletClient.getAddresses();
const originalMessage = "YOUR_MESSAGE";

// Sign the message
const hash = await walletClient.signMessage({
  account: address[0],
  message: originalMessage,
});

Sign Typed Data v4​

// SignTypedData in viem
// https://viem.sh/docs/actions/wallet/signTypedData

/*
  Use code from the above Initializing Provider here
*/

const walletClient = createWalletClient({
  chain: mainnet,
  transport: custom(this.provider),
});

const address = await walletClient.getAddresses();

const signature = await walletClient.signTypedData({
  account: address[0],
  domain: {
    name: "Ether Mail",
    version: "1",
    chainId: 1,
    verifyingContract: "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
  },
  types: {
    Person: [
      { name: "name", type: "string" },
      { name: "wallet", type: "address" },
    ],
    Mail: [
      { name: "from", type: "Person" },
      { name: "to", type: "Person" },
      { name: "contents", type: "string" },
    ],
  },
  primaryType: "Mail",
  message: {
    from: {
      name: "Cow",
      wallet: "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826",
    },
    to: {
      name: "Bob",
      wallet: "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB",
    },
    contents: "Hello, Bob!",
  },
});

Smart Contract​

Solidity Contract​

In this example, we'll be demonstrating how to use Web3Auth with web3.js or ethers.js to interact with Solidity smart contracts. The simple Hello World contract allows anyone to read and write a message to it.

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;

contract HelloWorld {

  string public message;

  constructor(string memory initMessage) {
    message = initMessage;
  }

  function update(string memory newMessage) public {
    message = newMessage;
  }
}

Deploy Contract​

/*
  Use code from the above Initializing Provider here
*/
const publicClient = createPublicClient({
  chain: this.getViewChain(),
  transport: custom(this.provider),
});

const walletClient = createWalletClient({
  chain: mainnet,
  transport: custom(this.provider),
});

const contractABI = [
  {
    inputs: [{ internalType: "string", name: "initMessage", type: "string" }],
    stateMutability: "nonpayable",
    type: "constructor",
  },
  {
    inputs: [],
    name: "message",
    outputs: [{ internalType: "string", name: "", type: "string" }],
    stateMutability: "view",
    type: "function",
  },
  {
    inputs: [{ internalType: "string", name: "newMessage", type: "string" }],
    name: "update",
    outputs: [],
    stateMutability: "nonpayable",
    type: "function",
  },
];
const contractByteCode =
  "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const [account] = await walletClient.getAddresses();
const hash = await walletClient.deployContract({
  abi: this.contractABI,
  account,
  bytecode: this.contractByteCode,
  args: ["Hello World!"],
});

const receipt = await publicClient.waitForTransactionReceipt({ hash });

const deployedContractAddress = receipt.contractAddress;

Read From Contract​

/*
  Use code from the above Initializing Provider here
*/

const contractABI = [
  {
    inputs: [{ internalType: "string", name: "initMessage", type: "string" }],
    stateMutability: "nonpayable",
    type: "constructor",
  },
  {
    inputs: [],
    name: "message",
    outputs: [{ internalType: "string", name: "", type: "string" }],
    stateMutability: "view",
    type: "function",
  },
  {
    inputs: [{ internalType: "string", name: "newMessage", type: "string" }],
    name: "update",
    outputs: [],
    stateMutability: "nonpayable",
    type: "function",
  },
];

const publicClient = createPublicClient({
  chain: mainnet, // for mainnet
  transport: custom(this.provider),
});

const contractAddress = "0x8AA6820B3F197384874fAdb355361758258cb981"; // On Sepolia, replace with your contract address

// Read message from smart contract
const message = await publicClient.readContract({
  address: contractAddress,
  abi: contractABI,
  functionName: "message",
});

Write to Contract​

/*
  Use code from the above Initializing Provider here
*/

const contractABI = [
  {
    inputs: [{ internalType: "string", name: "initMessage", type: "string" }],
    stateMutability: "nonpayable",
    type: "constructor",
  },
  {
    inputs: [],
    name: "message",
    outputs: [{ internalType: "string", name: "", type: "string" }],
    stateMutability: "view",
    type: "function",
  },
  {
    inputs: [{ internalType: "string", name: "newMessage", type: "string" }],
    name: "update",
    outputs: [],
    stateMutability: "nonpayable",
    type: "function",
  },
];
const publicClient = createPublicClient({
  chain: mainnet,
  transport: custom(this.provider),
});

const walletClient = createWalletClient({
  chain: mainnet,
  transport: custom(this.provider),
});

const contractAddress = "0x8AA6820B3F197384874fAdb355361758258cb981"; // On Sepolia, replace with your contract address
address = await walletClient.getAddresses();

// Submit transaction to the blockchain
const hash = await walletClient.writeContract({
  account: address[0],
  address: contractAddress,
  abi: JSON.parse(JSON.stringify(contractABI)),
  functionName: "update",
  args: ["NEW_MESSAGE"],
});

// Send transaction to smart contract to update message
const receipt = await publicClient.waitForTransactionReceipt({ hash });

Fetch User's Private Key​

eth_private_key is used to fetch the private key of the logged in user. It is only available for in-app adapters like openlogin.

//Assuming user is already logged in.
async getPrivateKey() {
  const privateKey = await web3auth.provider.request({
    method: "eth_private_key"
  });
  //Do something with privateKey
}