Ethereum hands on

Basic example how to read and write data on Ethereum blockchain with Web3.js framework.

Files

Project files

• Hello.sol : the smart contract

• src/index.html : the main file of the DApp

• src/lib/web3.min.js : the Web3.js framework, included in index.html

• src/blockchain.js : function to interact with blockchain, included in index.html

• src/lib/hello-abi.js : the smart contract interface, included in index.html

• src/app.js : Nodejs file to serve index.html from a server (mandatory to use Web3)

• PayableHello.sol : v2 of the smart contract

• src/lib/payable-hello-abi.js : the smart contract v2 interface, included in index.html

Miscellaneous

• docs/ : codelab files
• tools/truffle/ : Truffle files to generate ABI and deploy contract
• tools/save.sh : generate codelab from markdown file

Prerequisite

• Node.js

• Install Metamask on your browser (https://metamask.io/) and create an account.

• Request some test Ether on faucet (https://faucet.metamask.io/) on Ropsten test network.

Run

Deploy Hello.sol contract on blockchain.

Set contract address in blockchain.js

const contractAddress = "0x5749Fc6....";

After that, you can run the app :

cd src
node index.js

Then open browser at http://localhost:3000

Tutorial

https://avysel.github.io/ethereum-hands-on