README.md

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Tips

With example codes shown below, developers can learn the difference between web3.js and ethers.js

This project mainly focus on tasks including connect to ethereum , get accounts , deploy the contract , call methods of the contract .

Test

1. Install dependencies

yarn install

2. Run compile.js script

yarn compile

3. Start local test network

yarn chain

4. Run the test script

yarn test

Example explanation

1、connect to etherum

// web3.js

const web3 = new Web3('http://localhost:8545');
// or
const web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));

// ethers
const provider = new ethers.providers.JsonRpcProvider('http://localhost:8545');
const signer = provider.getSigner();

2、Get accounts

// ethers
const provider = new ethers.providers.JsonRpcProvider('http://localhost:8545');
const accounts1 = await provider.listAccounts();

// web3.js
const web3 = new Web3('http://127.0.0.1:8545');
const accounts2 = await web3.eth.getAccounts();

3、Deploy the contract

// using ethers
//  deploying contract with ethers needs abi, bytecode, signer.
const factory = new ethers.ContractFactory(abi, bytecode, signer);
const contractInstance = await factory.deploy(0);
const tx = await contractInstance.deployTransaction.wait();
console.log(tx);
console.log('Contract deployed at address:', contractInstance.address);

// using web3
const accounts = await web3.eth.getAccounts();
const contract = new web3.eth.Contract(abi);
const tx = contract.deploy({
  data: bytecode,
  arguments: [0],
});
// const deployReceipt = tx.send({
//   from: accounts[0],
//   gas: gasLimit,
//   gasPrice,
// });
// deployReceipt.on('receipt', function (receipt) {
//   console.log(`Contract deployed at address: ${receipt.contractAddress}`);
// });
const contractInstance = await tx.send({
  from: accounts[0],
  gas: gasLimit,
  gasPrice,
});
console.log('Contract deployed at address:', contractInstance.options.address);

4、Call methods：

Call method without transaction：

// Web3.js
const contractInstance = new web3.eth.Contract(abi, contractAddress);
let currentValue = await contractInstance.methods.currentValue().call();
console.log('Incrementer Contract currentValue:', currentValue);

// ethers
const readContract = new ethers.Contract(contractAddress, abi, provider);
let currentValue = await readContract.currentValue();
console.log('Incrementer Contract currentValue:', currentValue.toString());

Call method with transaction：

// Web3.js
const accounts = await web3.eth.getAccounts();
const contractInstance = new web3.eth.Contract(abi, contractAddress);
const tx = contractInstance.methods.descrement(1);
await tx
  .send({
    from: accounts[0],
    gas: gasLimit,
    gasPrice,
  })
  .on('receipt', async (recepit) => {
    currentValue = await contractInstance.methods.currentValue().call();
    console.log('Incrementer Contract currentValue:', currentValue);
  });

// ethers
const writeContract = new ethers.Contract(contractAddress, abi, signer);
const tx = await writeContract.increment(ethers.BigNumber.from(5));
await tx.wait();
currentValue = await readContract.currentValue();
console.log('Incrementer Contract currentValue:', currentValue.toString());

Query events

// written in etherjs
const readContract = new ethers.Contract(contractAddress, abi, provider);
// The parameters passed to filters can only be indexed parameters.
const filter = readContract.filters.Bid(null, utils.hexlify(BigNumber.from(auction.recordId)));
// Filter the blocks
const logsFrom = await readContract.queryFilter(filter, 0, "latest");
logsFrom.forEach(item => console.log(items.args));

// written in web3
const web3 = new Web3(provider);
const contractInstance = new web3.eth.Contract(abi, contractAddress);
const logs = await contractInstance.getPastEvents('Descrement', {
  filter: {},
  fromBlock: 0,
});

logs.forEach((item) => {
  console.log('Descrement Event:', item); // same results as the optional callback above
});

Subscribe events

const provider = new ethers.providers.JsonRpcProvider('http://localhost:8545');
// http provider does not support subscription
const web3 = new Web3(new Web3.providers.WebsocketProvider('ws://localhost:8545'));

  // using ethers
  async function subByEthers() {
    const readContract = new ethers.Contract(contractAddress, abi, provider);
    let filterForm = readContract.filters.Increment();
    readContract.on(filterForm, (amount, event) => {
      console.log('Increment events:', event);
    });
  }
  subByEthers();

  
  // using web3
  async function subByWeb3() {
    const contractInstance = new web3.eth.Contract(abi, contractAddress);
    contractInstance.events
      .Descrement({
        fromBlock: 0,
      })
      .on('data', (event) => {
        console.log('Descrement Event:', event); // same results as the optional callback above
      })
      .on('error', function (error, receipt) {
        console.error('Descrement Event error:', error);
      });
  }
  subByWeb3();
}

const server = http.createServer(() => {});
server.listen(8002);

Reference

1 - web3-vs-ethers

2 - web3js doc

3 - ethers doc