How to Build Your DApp Using The Modern Ethereum Tech Stack: Hardhat and EthersJs

npx create-react-app moDappTut

npm install ethers hardhat @nomiclabs/hardhat-waffle ethereum-waffle @nomiclabs/hardhat-ethers chai

npx hardhat

//MDToken.sol
//SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.7.0;
contract Token {
    string public name = "Madfinger Token";
    string public symbol = "MHT";
    // The fixed amount of tokens stored in an unsigned integer type variable.
    uint256 public totalSupply = 1000000;
    // An address type variable is used to store ethereum accounts.
    address public owner;
    // A mapping is a key/value map. Here we store each account balance.
    mapping(address => uint256) balances;
    /**
     * Contract initialization.
     *
     * The `constructor` is executed only once when the contract is created.
     * The `public` modifier makes a function callable from outside the contract.
     */
    constructor() {
        // The totalSupply is assigned to transaction sender, which is the account
        // that is deploying the contract.
        balances[msg.sender] = totalSupply;
        owner = msg.sender;
    }
    /**
     * A function to transfer tokens.
     *
     * The `external` modifier makes a function *only* callable from outside
     * the contract.
     */
    function transfer(address to, uint256 amount) external {
        // Check if the transaction sender has enough tokens.
        // If `require`'s first argument evaluates to `false` then the
        // transaction will revert.
        require(balances[msg.sender] >= amount, "Not enough tokens");
        // Transfer the amount.
        balances[msg.sender] -= amount;
        balances[to] += amount;
    }
    /**
     * Read only function to retrieve the token balance of a given account.
     *
     * The `view` modifier indicates that it doesn't modify the contract's
     * state, which allows us to call it without executing a transaction.
     */
    function balanceOf(address account) external view returns (uint256) {
        return balances[account];
    }
}

npx hardhat node

//deploy.js
const hre = require("hardhat");
async function main() {
    // ethers is avaialble in the global scope
    const [deployer] = await hre.ethers.getSigners();
    console.log(
      "Deploying the contracts with the account:",
      await deployer.getAddress()
    );

    console.log("Account balance:", (await deployer.getBalance()).toString());

    const Token = await hre.ethers.getContractFactory("Token");
    const token = await Token.deploy();
    await token.deployed();

    console.log("Token address:", token.address);

  }

  main()
    .then(() => process.exit(0))
    .catch((error) => {
      console.error(error);
      process.exit(1);
    });

//hardhat.config.js
module.exports = {
  paths: {
    artifacts: './src/artifacts',
  },
  solidity: "0.8.4",
};

npx hardhat run --network localhost scripts/deploy.js

npm start

// src/app.js
import './App.css';
import {ethers} from 'ethers'
import { useState } from 'react';
import TokenArtifact from "./artifacts/contracts/Token.sol/Token.json"
const tokenAddress = "0x5FbDB2315678afecb367f032d93F642f64180aa3"


function App() {
 const [tokenData, setTokenData] = useState({})
 const [amount, setAmount] = useState()
 const [userAccountId, setUserAccountId] = useState()

async function requestAccount() {
  await window.ethereum.request({ method: 'eth_requestAccounts' });
}

 const provider = new ethers.providers.Web3Provider(window.ethereum);
 const signer = provider.getSigner();
 async function _intializeContract(init) {
  // We first initialize ethers by creating a provider using window.ethereum
  // When, we initialize the contract using that provider and the token's
  // artifact. You can do this same thing with your contracts.
  const contract = new ethers.Contract(
    tokenAddress,
    TokenArtifact.abi,
    init
  );

  return contract
}
 async function _getTokenData() {
  const contract = await _intializeContract(signer)
  const name = await contract.name();
  const symbol = await contract.symbol();
  const tokenData = {name, symbol}
  setTokenData(tokenData);
}
async function sendMDToken() {
  if (typeof window.ethereum !== 'undefined') {
    await requestAccount()
    const contract = await _intializeContract(signer)
    const transaction = await contract.transfer(userAccountId, amount);
    await transaction.wait();
    console.log(`${amount} MDToken has been sent to ${userAccountId}`);
  }
}
async function getBalance() {
  if (typeof window.ethereum !== 'undefined') {
    const contract = await _intializeContract(signer)
    const [account] = await window.ethereum.request({ method: 'eth_requestAccounts' })
    const balance = await contract.balanceOf(account);
    console.log("Account Balance: ", balance.toString());
  }
}
  return (
    <div className="App">
      <header className="App-header">
      <button onClick={_getTokenData}>get token data</button>
      <h1>{tokenData.name}</h1>
      <h1>{tokenData.symbol}</h1>
      <button onClick={getBalance}>Get Balance</button>
      <button onClick={sendMDToken}>Send MDToken</button>
      <input onChange={e => setUserAccountId(e.target.value)} placeholder="Account ID" />
        <input onChange={e => setAmount(e.target.value)} placeholder="Amount" />
      </header>
    </div>
  );
}
export default App;

async function requestAccount() {
  await window.ethereum.request({ method: 'eth_requestAccounts' });
}

 const provider = new ethers.providers.Web3Provider(window.ethereum);
 const signer = provider.getSigner();
 async function _intializeContract(init) {
  // We first initialize ethers by creating a provider using window.ethereum
  // When, we initialize the contract using that provider and the token's
  // artifact. You can do this same thing with your contracts.
  const contract = new ethers.Contract(
    tokenAddress,
    TokenArtifact.abi,
    init
  );

  return contract
}

return (
    <div className="App">
      <header className="App-header">
      <button onClick={_getTokenData}>get token data</button>
      <h1>{tokenData.name}</h1>
      <h1>{tokenData.symbol}</h1>
      <button onClick={getBalance}>Get Balance</button>
      <button onClick={sendMDToken}>Send MDToken</button>
      <input onChange={e => setUserAccountId(e.target.value)} placeholder="Account ID" />
        <input onChange={e => setAmount(e.target.value)} placeholder="Amount" />
      </header>
    </div>
  );

async function _getTokenData() {
  const contract = await _intializeContract(signer)
  const name = await contract.name();
  const symbol = await contract.symbol();
  const tokenData = {name, symbol}
  setTokenData(tokenData);
}

async function getBalance() {
  if (typeof window.ethereum !== 'undefined') {
    const contract = await _intializeContract(signer)
    const [account] = await window.ethereum.request({ method: 'eth_requestAccounts' })
    const balance = await contract.balanceOf(account);
    console.log("Account Balance: ", balance.toString());
  }
}

async function sendMDToken() {
  if (typeof window.ethereum !== 'undefined') {
    await requestAccount()
    const contract = await _intializeContract(signer)
    const transaction = await contract.transfer(userAccountId, amount);
    await transaction.wait();
    console.log(`${amount} MDToken has been sent to ${userAccountId}`);
  }
}