Transaction-ethereum-smart-contract

Transaction-ethereum-smart-contract.js

var Web3 = require("web3");
// TO make a transaction from a wallet address to a smart contract address
// The smart contract has a function called : `set()`, which set a value to the data for the variable called : `data`


const init2 = async () => {
  try {
    const provider = new Web3.providers.HttpProvider(endPoint); // https://ropsten.infura.io/v3/ROPSTEN_API_KEY
    web3 = new Web3(provider);
    web3.eth.handleRevert = true;
    let testContract = await new web3.eth.Contract(abi, addressOfContract); //abi = smart contract JSON
    web3.eth.accounts.wallet.add(privateKey); // Wallet privateKey (mine, with some token on it to pay the gaz.)
    const tx = testContract.methods.set(2); // set() is a method I made on the smart contract
    const gas = await tx.estimateGas({ from: address }); // my public wallet address 
    const gasPrice = await web3.eth.getGasPrice();
    const data = tx.encodeABI();
    const nonce = await web3.eth.getTransactionCount(address);
    const txData = {
      from: address,
      to: addressOfContract,
      data: data,
      gas,
      gasPrice,
      nonce,
      //chain: "ropsten",
      //hardfork: "istanbul", About hardfork: https://www.investopedia.com/terms/h/hard-fork.asp
    };
    console.log(`Old data value: ${await testContract.methods.get().call()}`); // Method to call the other method of the contract : `get()`, which gives me the current `data` variable.
    const receipt = await web3.eth.sendTransaction(txData);
    console.log(`Transaction hash: ${receipt.transactionHash}`);  // We can check the transaction online with that hash at : https://ropsten.etherscan.io/tx/
    console.log(`New data value: ${await testContract.methods.get().call()}`);
  } catch (error) {
    console.log(error, "error init2()");
  }
};

init2()