Learn TRUFFLE with Real Code Examples

// contracts/Counter.sol
pragma solidity ^0.8.0;

contract Counter {
    uint256 public count = 0;
    function increment() public { count += 1; }
}

// migrations/2_deploy_contracts.js
const Counter = artifacts.require('Counter');
module.exports = function(deployer) {
    deployer.deploy(Counter);
};

// Run using `truffle migrate`

A minimal example showing how to deploy a simple smart contract using Truffle.

const Counter = artifacts.require('Counter');

module.exports = async function(callback) {
    const counter = await Counter.deployed();
    console.log('Initial count:', (await counter.count()).toString());
    await counter.increment();
    console.log('Updated count:', (await counter.count()).toString());
    callback();
};

Interact with a deployed Truffle contract using JavaScript.

const Payment = artifacts.require('Payment');

module.exports = async function(callback) {
    const payment = await Payment.deployed();
    await payment.sendTransaction({ from: web3.eth.accounts[0], value: web3.utils.toWei('1', 'ether') });
    console.log('Payment sent');
    callback();
};

Send Ether to a contract using Truffle's JS interface.

const Counter = artifacts.require('Counter');

module.exports = async function(callback) {
    const counter = await Counter.deployed();
    counter.CounterIncremented().on('data', event => {
        console.log('Event:', event.returnValues);
    });
    callback();
};

Listen to events emitted by a Truffle contract.

// contracts/Greeter.sol
pragma solidity ^0.8.0;

contract Greeter {
    string public greeting;
    constructor(string memory _greeting) {
        greeting = _greeting;
    }
}

// migrations/2_deploy_contracts.js
const Greeter = artifacts.require('Greeter');
module.exports = function(deployer) {
    deployer.deploy(Greeter, 'Hello Truffle');
};

Deploy a contract with constructor parameters using Truffle.

const Greeter = artifacts.require('Greeter');

module.exports = async function(callback) {
    const greeter = await Greeter.deployed();
    const message = await greeter.greeting();
    console.log('Greeting:', message);
    callback();
};

Call a read-only function from a deployed contract using Truffle.

const MyToken = artifacts.require('MyToken');

module.exports = async function(callback) {
    const token = await MyToken.deployed();
    await token.transfer(web3.eth.accounts[1], 100);
    console.log('Tokens transferred');
    callback();
};

Interact with an ERC20 token contract deployed via Truffle.

const Counter = artifacts.require('Counter');

module.exports = async function(callback) {
    const counter = await Counter.deployed();
    const gas = await counter.increment.estimateGas();
    console.log('Estimated gas:', gas);
    callback();
};

Estimate gas usage for a contract function call.

const Counter = artifacts.require('Counter');

module.exports = async function(callback) {
    const counter = await Counter.deployed();
    const events = await counter.getPastEvents('CounterIncremented', { fromBlock: 0, toBlock: 'latest' });
    console.log(events);
    callback();
};

Fetch past events emitted by a deployed contract.

const Payment = artifacts.require('Payment');

module.exports = async function(callback) {
    const payment = await Payment.deployed();
    await payment.pay({ from: web3.eth.accounts[0], value: web3.utils.toWei('0.5', 'ether') });
    console.log('Payment transaction completed');
    callback();
};

Send a transaction with Ether to a function that is payable.